DirectX Basic Triangle Transparency

Hi. Im new to direct x, i only need simple functionality for my project. it will just be a load of cubes in an n*n*n grid where each block can be colorized and have its transparency altered. Im haveing a problem setting transparency which is to me more important that color. Hear is my test application. I create a cube but in the "device.DrawUserPrimitives(PrimitiveType.TriangleList,(vir.Length/3)-6,vir);" i only show half the sides so that i can test transparency.
I have looked hard and long to find the solution but with no joy. If anyone can help i would be a very happy man. the color is applied in the initVertecies() method and the scene is in draw() Method. Thankyou.

Code:

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using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using Microsoft.DirectX.Direct3D;
using Microsoft.DirectX;

using Microsoft.DirectX.PrivateImplementationDetails;

namespace DirectX_9_Test
{

        public partial class ViewPort : UserControl
        {
                private Point_3 CamPos=new Point_3();
                Collection<Point_3> p3VerteciesList;
                public bool isDeviceReady=false;
                public Microsoft.DirectX.Direct3D.Device device;
                CustomVertex.PositionColored[] vir;
                public ViewPort()
                {
                        //
                        // The InitializeComponent() call is required for Windows Forms designer support.
                        //
                        InitializeComponent();
                        InitDirectX();
                       
                        //
                        // TODO: Add constructor code after the InitializeComponent() call.
                        //
                }
               
                private void InitDirectX()
                {
                        PresentParameters presentParams=new PresentParameters();
                        presentParams.Windowed=true;
                        presentParams.SwapEffect=SwapEffect.Discard;
                        device=new Microsoft.DirectX.Direct3D.Device(0,Microsoft.DirectX.Direct3D.DeviceType.Hardware,this,CreateFlags.HardwareVertexProcessing,presentParams);
                        device.RenderState.SourceBlend = Blend.SourceAlpha;
                        device.RenderState.DestinationBlend = Blend.InvSourceAlpha;
                }
               
                public void initCamra()
                {
                        device.Transform.Projection=Matrix.PerspectiveFovLH((float)(Math.PI/4),(float)(Width/Height),1f,500f);
                        device.Transform.View=Matrix.LookAtLH(new Vector3((float)CamPos.x,(float)CamPos.y,(float)CamPos.z),new Vector3(),new Vector3(0f,1f,0f));
                        device.RenderState.Lighting=false;
                        device.RenderState.CullMode=Cull.None;
                }
                private void initVertecies()
                {
                        p3VerteciesList=Block.StandardBlock();
                        vir=new CustomVertex.PositionColored[p3VerteciesList.Count];
                        int n=0;
                        foreach(Point_3 p in p3VerteciesList)
                        {
                                vir[n].Position=new  Vector3((float)p.x*50,(float)p.y*50,(float)p.z*50);
                                vir[n].Color=(new ColorValue(255,2,0,255/2).ToArgb());
                                n++;
                        }
                }
                private void Draw()
                {
                        device.VertexFormat=CustomVertex.PositionColored.Format;
                        device.DrawUserPrimitives(PrimitiveType.TriangleList,(vir.Length/3)-6,vir);
                       
                }
                protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
                {
                        initVertecies();
                        initCamra();
                        device.Clear(ClearFlags.Target,Color.White,1.0f,0);
                        device.BeginScene();
                        Draw();
                        device.EndScene();
                        device.Present();
                }
               
                public void ViewPortKeyPress(object sender, KeyPressEventArgs e)
                {
                        char c=e.KeyChar;
                        switch(c)
                        {
                                case ' ':
                                        CamPos.y++;
                                        this.Invalidate();
                                        break;
                                case 'x':
                                        CamPos.y--;
                                        this.Invalidate();
                                        break;
                                case 'w':
                                        CamPos.z++;
                                        this.Invalidate();
                                        break;
                                case 's':
                                        CamPos.z--;
                                        this.Invalidate();
                                        break;
                                case 'a':
                                        CamPos.x++;
                                        this.Invalidate();
                                        break;
                                       
                                case 'd':
                                        CamPos.x--;
                                        this.Invalidate();
                                        break;
                        }
                       
                }
        }
       
        public class Block
        {
                public static Collection<Point_3> StandardBlock()
                {Point_3 a,b,c,d,e,f,g,h;
                        a=new Point_3(-0.5f,0.5f,-0.5f);
                        b=new Point_3(0.5f,0.5f,-0.5f);
                        c=new Point_3(0.5f,0.5f,0.5f);
                        d=new Point_3(-0.5f,0.5f,0.5f);
                        e=new Point_3(0.5f,-0.5f,-0.5f);
                        f=new Point_3(-0.5f,-0.5f,-0.5f);
                        g=new Point_3(0.5f,-0.5f,0.5f);
                        h=new Point_3(-0.5f,-0.5f,0.5f);
                        Collection<Point_3> block=new Collection<Point_3>();
                        block.Add(d);block.Add(g);block.Add(h);
                        block.Add(d);block.Add(c);block.Add(g);
                        block.Add(c);block.Add(e);block.Add(g);
                        block.Add(c);block.Add(b);block.Add(e);
                        block.Add(b);block.Add(f);block.Add(e);
                        block.Add(b);block.Add(a);block.Add(f);
                        block.Add(a);block.Add(h);block.Add(f);
                        block.Add(a);block.Add(d);block.Add(h);
                        block.Add(a);block.Add(c);block.Add(d);
                        block.Add(a);block.Add(b);block.Add(c);
                        block.Add(h);block.Add(e);block.Add(f);
                        block.Add(h);block.Add(g);block.Add(e);
                        return block;
                }
        }
       
        public class Point_3
        {
                public double x=0,y=0,z=0;
                public Point_3()
                {
                       
                }
                public Point_3(double x,double y,double z)
                {
                        this.x=x;this.y=y;this.z=z;
                }
        }
}

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I have enabled the ZBuffer, as i guess we cant sort the transparency without it. I have also added another cube so i can show all sides, however when i use the ClearFlags.ZBuffer when i clear, i get no more output on the screen. if i do not use this flag i get no output in the world space where a polygon has already been. So im haveing no luck. Please help. once i get past this i can get into some real cool 3d fractal code and have lots of fun. I dont want to have to create my own renderer because it will be to slow. use too much memory or disk I/O operations and it will take me a few weeks to compleat. Plus i want to make good use of my Graphics cards. Thankyou

The z-buffer approach won't work for transparent surfaces. This is because transparent surfaces affect the colour behind them, so what is behind them must have already been drawn.

Using a z-buffer you have to:
1) Draw non-transparent surfaces (any order will do) using z-buffer
2) Draw transparent surfaces in back-to-front order, using same z-buffer.

It is also sensible to draw the non-transparent surfaces in front-to-back order (as much as possible) as this cuts down the amount of processing needed for calculating shading/texturing.

Thankyou Peter_B, Ill give that a try.