Error ?? why ?

[spoiledkid]

I declared a delegate in one of my classes.

Private Delegate Sub AsyncDelegate(ByVal ar As IAsyncResult)

And I am using it to asynchronously fetch and load data in my grid.

Private Sub CallBackGrid(ByVal ar As IAsyncResult)
        If ar Is Nothing Then
            m_waitWindow.lblMessage.Text = "Please wait.. while Loading Grid."
            m_waitWindow.Show()
            Dim RunDelegate As AsyncDelegate = AddressOf FillGrid
            RunDelegate.BeginInvoke(ar, AddressOf CallBackGrid, RunDelegate)
        ElseIf ar.IsCompleted Then
            m_waitWindow.Hide()
        End If
    End Sub
 
    Private Sub FillGrid(ByVal ar As IAsyncResult)
        Dim entityObject As New B_Entity
        Dim whereClause, orderBy As String
        Dim entitySchema As String
        Dim recordCount As Long
 
        If txtLabel.Text.Trim <> "" Then
            whereClause = "Label Like '" & txtLabel.Text & "%'"
        End If
        If txtParentEntity.Text.Trim <> "" Then
            whereClause = "ParentEntity Like '" & txtParentEntity.Text & "'"
        End If
        If txtTableName.Text.Trim <> "" Then
            whereClause = "TableName Like '" & txtTableName.Text & "'"
        End If
        If txtLevel.Text.Trim <> "" Then
            whereClause = "Level = " & txtLevel.Text
        End If
 
        orderBy = "TableName ASC"
        whereClause = ""
        orderBy = ""
 
        Try
 
            Dim entityData As DataTable = entityObject.GetEntities(m_Page, CType(txtRecordsPerPage.Text, Integer), "*", "CRM_UDF_GetConfig_Entities()", whereClause, orderBy, recordCount)
            entitySchema = "Entity_Guid,ParentEntity_Guid,TableName,SortOrder,Level,Entity_Label,ParentEntity_Label,Active"
 
            spdEntities.ActiveSheet.RowCount = entityData.Rows.Count
 
            Dim i, j As Integer
 
            For i = 0 To entityData.Rows.Count - 1
                spdEntities.ActiveSheet.SetActiveCell(i, 1)
                spdEntities.ActiveSheet.Cells(i, 1).Value = entityData.Rows(0)("Entity_Guid").ToString
                spdEntities.ActiveSheet.Cells(i, 2).Value = entityData.Rows(0)("ParentEntity_Guid").ToString
                spdEntities.ActiveSheet.Cells(i, 3).Value = entityData.Rows(0)("Entity_Label").ToString
                spdEntities.ActiveSheet.Cells(i, 4).Value = entityData.Rows(0)("ParentEntity_Label").ToString
                spdEntities.ActiveSheet.Cells(i, 5).Value = entityData.Rows(0)("TableName").ToString
                spdEntities.ActiveSheet.Cells(i, 6).Value = entityData.Rows(0)("SortOrder").ToString
                spdEntities.ActiveSheet.Cells(i, 7).Value = entityData.Rows(0)("Level").ToString
 
                spdEntities.ActiveSheet.Cells(i, 8).Value = entityData.Rows(0)("Active")
            Next
 
            txtTotalRecords.Text = CType(recordCount, String)
 
        Catch ex As Exception
            Debug.WriteLine(ex.Message)
        End Try
    End Sub

It gives this error message.

An unhandled exception of type 'System.IndexOutOfRangeException' occurred in system.windows.forms.dll

Additional information: Invalid row index: 0 (must be between -1 and -1).

But when I comment all the CallBackGrid code and put only one line FillGrid(nothing), it works like a charm. What is wrong with delegate I do not understand.

[Pirate]

See if you can get any clue after reading this tutorial , hopefully .
http://www.devx.com/codemag/Article/21100/0/page/1

[spoiledkid]

It says page cannot be displayed error ... but do you see any reason why I should be getting that error ???

[Pirate]

The link is working . I'm sorry if I can't offer more help as I've never worked yet with asynchronous operations .