where is the error?why I can not export the report?

webform1.aspx.vb:

Imports System
Imports System.Data
Imports System.Web.UI
Imports System.Web
Imports System.Web.UI.Control
Public Class WebForm1
Inherits System.Web.UI.Page
Protected WithEvents DropDownList1 As System.Web.UI.WebControls.DropDownList
Protected WithEvents TextBox1 As System.Web.UI.WebControls.TextBox
Protected WithEvents Button1 As System.Web.UI.WebControls.Button
Protected WithEvents Label3 As System.Web.UI.WebControls.Label
Protected WithEvents Label2 As System.Web.UI.WebControls.Label
Protected WithEvents Label1 As System.Web.UI.WebControls.Label
Protected WithEvents Label4 As System.Web.UI.WebControls.Label
Protected WithEvents Label5 As System.Web.UI.WebControls.Label
Protected WithEvents TextBox2 As System.Web.UI.WebControls.TextBox
Protected WithEvents TextBox3 As System.Web.UI.WebControls.TextBox
Protected WithEvents Label6 As System.Web.UI.WebControls.Label
Protected WithEvents Label7 As System.Web.UI.WebControls.Label
Protected WithEvents TextBox4 As System.Web.UI.WebControls.TextBox
Protected WithEvents Label8 As System.Web.UI.WebControls.Label
Protected WithEvents RequiredFieldValidator1 As System.Web.UI.WebControls.RequiredFieldValidator
Protected WithEvents RequiredFieldValidator2 As System.Web.UI.WebControls.RequiredFieldValidator
Protected WithEvents Button2 As System.Web.UI.HtmlControls.HtmlInputButton
Protected WithEvents DropDownList2 As System.Web.UI.WebControls.DropDownList

#Region " Web ´°ÌåÉè¼ÆÆ÷Éú³ÉµÄ´úÂë "

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<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

End Sub

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: ´Ë·½·¨µ÷ÓÃÊÇ Web ´°ÌåÉè¼ÆÆ÷Ëù±Ø�èµÄ
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InitializeComponent()
End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'ÔÚ´Ë´¦·ÅÖóõʼ»¯Ò³µÄÓû§´úÂë
Dim strConnection As String = "user id=sa; password=;"
strConnection += "database=salesys;server=LI_XIANG\lx;"
Dim strSql As String = "select distinct customer_id,company_name from jianglijinchaxun "
Dim objConnection As SqlConnection = New SqlConnection(strConnection)
Dim objDataset As New DataSet()
Dim objDataadapter As New SqlDataAdapter(strSql, objConnection)
objDataadapter.Fill(objDataset, "jianglijinchaxun")
Dim objDataview As New DataView(objDataset.Tables("jianglijinchaxun"))
Dim objTable As DataTable
objTable = objDataset.Tables("jianglijinchaxun")

Dim strCustomer_id(65) As String
Dim i As Integer
For i = 0 To 64
strCustomer_id(i) = objTable.Rows(i).Item("customer_id")
Next

Dim strid As String
For Each strid In strCustomer_id
DropDownList1.Items.Add(strid)
Next


'²úÆ·µÄ´úÂë°ó¶¨
End Sub

Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
Dim strConnection As String = "user id=sa; password=;"
strConnection += "database=salesys;server=LI_XIANG\lx;"
Dim strSql As String = "select distinct customer_id,company_name from jianglijinchaxun "
Dim objConnection As SqlConnection = New SqlConnection(strConnection)
Dim objDataset As New DataSet()
Dim objDataadapter As New SqlDataAdapter(strSql, objConnection)
objDataadapter.Fill(objDataset, "jianglijinchaxun")
Dim objDataview As New DataView(objDataset.Tables("jianglijinchaxun"))
Dim objTable As DataTable
objTable = objDataset.Tables("jianglijinchaxun")
If DropDownList1.SelectedItem.Value = "" Then
TextBox1.Text = ""
Else
TextBox1.Text = objTable.Rows(DropDownList1.SelectedIndex).Item("company_name")
End If

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Response.Redirect("webform2.aspx?customerid=" + Server.UrlEncode(DropDownList1.SelectedItem.Value) + "&productid=" + Server.UrlEncode(DropDownList2.SelectedItem.Value) _
+ "&startdate=" + Server.UrlEncode(TextBox2.Text) + "&enddate=" + Server.UrlEncode(TextBox3.Text))
End Sub




End Class



webform2.aspx.vb



Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Data
Imports System.Web
Imports System.Web.SessionState
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Imports CrystalDecisions.Shared
Imports CrystalDecisions.CrystalReports.Engine

Public Class WebForm2
Inherits System.Web.UI.Page
Dim strCustomerid As String
Dim strProductid As String
Dim strStartdate As String
Dim strEnddate As String
Protected WithEvents CrystalReportViewer1 As CrystalDecisions.Web.CrystalReportViewer
Protected WithEvents Button1 As System.Web.UI.WebControls.Button
Dim objdocument As New ReportDocument()
#Region " Web ´°ÌåÉè¼ÆÆ÷Éú³ÉµÄ´úÂë "

'¸Ãµ÷ÓÃÊÇ Web ´°ÌåÉè¼ÆÆ÷Ëù±Ø�èµÄ¡£
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

End Sub

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: ´Ë·½·¨µ÷ÓÃÊÇ Web ´°ÌåÉè¼ÆÆ÷Ëù±Ø�èµÄ
'²»ÒªÊ¹ÓôúÂë±Ã*¼_Æ÷Ã�Þ¸ÄËü¡£
InitializeComponent()

End Sub

#End Region

Public Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'ÔÚ´Ë´¦·ÅÖóõʼ»¯Ò³µÄÓû§´úÂë

strCustomerid = Request.QueryString.Get("customerid")
strProductid = Request.QueryString.Get("productid")
strStartdate = DateTime.Parse(Request.QueryString.Get("startdate"))
strEnddate = DateTime.Parse(Request.QueryString.Get("enddate"))

setreportparameters()

objdocument.Load("c:\\inetpub\\wwwroot\\asp\\report1\\CrystalReport1.rpt")
CrystalReportViewer1.ReportSource = objdocument
End Sub
Public Sub setreportparameters()
'ÉùÃ÷Ò»¸ö¼¯º�ÓÃÀ´×°²ÎÊý¶Ô�ó
Dim paramFields As New ParameterFields()
'½«Òª´«µ�µÄ²ÎÊý¶Î
Dim pfcustomerid As New ParameterField()
Dim pfproductid As New ParameterField()
Dim pfstartdate As New ParameterField()
Dim pfenddate As New ParameterField()
'ÉèÖòÒÊý×Ö¶ÎÃû
pfcustomerid.ParameterFieldName = "pcustomerid"
pfproductid.ParameterFieldName = "pproductid"
pfstartdate.ParameterFieldName = "pstartdate"
pfenddate.ParameterFieldName = "penddate"
'ÒÔÉ�²ÎÊý×Ö¶ÎÒª±»ÃØÃܶÔ�ó½ÓÊÜ
'ÉùÃ÷ÃØÃܶÔ�ó
Dim dccustomerid As New ParameterDiscreteValue()
Dim dcproductid As New ParameterDiscreteValue()
Dim dcstartdate As New ParameterDiscreteValue()
Dim dcenddate As New ParameterDiscreteValue()
'ÉèÖÃÖµ¸øÃØÃܶÔ�ó
dccustomerid.Value = strCustomerid
dcproductid.Value = strProductid
dcstartdate.Value = strStartdate
dcenddate.Value = strEnddate
'ÔÚ²ÎÊýÖ�¼ÓÈëÃØÃÜÖµ
pfcustomerid.CurrentValues.Add(dccustomerid)
pfproductid.CurrentValues.Add(dcproductid)
pfstartdate.CurrentValues.Add(dcstartdate)
pfenddate.CurrentValues.Add(dcenddate)
'�ÖÔÚ°ÑËùÓ�µÄ²ÎÊý×ֶμÓÈ뼯º�
paramFields.Add(pfcustomerid)
paramFields.Add(pfproductid)
paramFields.Add(pfstartdate)
paramFields.Add(pfenddate)
'×îºó°Ñ¼¯ºÃ�¼ÓÈëµ½±¨±Ã*ÖÃ�
CrystalReportViewer1.ParameterFieldInfo = paramFields

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
' ÉùÃ÷±ä�¿²¢»ñÈ¡µ¼³öÑ¡�î¡£
Dim exportOpts As New ExportOptions()
Dim DiskOpts As CrystalDecisions.Shared.DiskFileDestinationOptions = New CrystalDecisions.Shared.DiskFileDestinationOptions()
Dim excelFormatOpts As New ExcelFormatOptions()
exportOpts = objdocument.ExportOptions

' ÉèÖà Excel ¸ñʽѡ�î¡£
excelFormatOpts.ExcelTabHasColumnHeadings = True

objdocument.ExportOptions.ExportFormatType = ExportFormatType.Excel
objdocument.ExportOptions.FormatOptions = excelFormatOpts


' ÉèÖõ¼³ö¸ñʽ¡£
exportOpts.ExportFormatType = ExportFormatType.Excel

exportOpts.ExportDestinationType = ExportDestinationType.DiskFile

' ÉèÖôÅÅÌÎļþÑ¡�î²¢µ¼³ö¡£
DiskOpts.DiskFileName = "c:\output.xls"
objdocument.ExportOptions.DestinationOptions = DiskOpts

objdocument.Export()

End Sub
end class