Weird: Control does not appear in container control.

Using: Visual Studio 2008, Framework 3.5.

I tried creating a control that contains a textbox and a label and then resize itself to fit these things. I then tried to add this to a control whose parent is the form.

public TestTopControl(TestTopControlSettings sis)
{
this.ModelChaned +=new ViewDelegates.ModelChangedEventHandler(UseNewData);
this.Name = "Testname";
this.Location = new Point(sis.XLocation, sis.YLocation);
this.PropertyName = sis.Target;
this.Size = new Size(300, 300);
testComboBox = new TestComboBox();
testComboBox.Location = new Point(50, 50);
this.Controls.Add(testComboBox);
TestInput1 = new FloatInput(100, 100, "Test", "Test: This works.", 50);
TestInput2 = new StringInput(100, 130, "Test", "This should work aswell", 50);
this.Controls.Add(TestInput2);
this.Controls.Add(TestInput1);

testComboBox.SelectedIndexChanged += new EventHandler(testComboBox_SelectedIndexChanged);
Application.Idle += new EventHandler(Application_Idle);
}

this generates output according to works.jpg in attached files. If I just change the order in which the controls are added to TestTopControl it generates output according to works1.jpg. Am I missing something basic here? Here is the code for the baseclass of these classes:

public TextBoxInput(int xLocation, int yLocation, string target, string label, int boxWidth)
{
this.Controls.Add(inputLabel);
this.Controls.Add(inputBox);
this.Name = "Testnamel";
this.AutoSize = true;
this.inputLabel.Text = label;
this.inputLabel.AutoSize = true;
int width = inputLabel.Width;
this.inputLabel.AutoSize = false;
inputLabel.Width = width;
inputLabel.Height = inputBox.Height;
this.inputBox.Width = boxWidth;
this.inputBox.Location = new Point(inputLabel.Width, 0);
this.inputLabel.Location = new Point(0, 0);
Point p = new Point((xLocation - inputLabel.Width), (yLocation - (inputBox.Height/2)));
this.PropertyName = target;
this.inputLabel.TextAlign = ContentAlignment.MiddleLeft;
this.Location = p;
this.inputBox.LostFocus += new EventHandler(inputBox_LostFocus);
this.inputBox.KeyDown += new KeyEventHandler(inputBox_KeyDown);
this.modelChanged += new ViewDelegates.ModelChangedEventHandler(UseNewData);
}

edit: Weird, it works if the control instantiated last is added first.. Any idea why?