Question

Code for button:

Protected Sub btnAdd_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAdd.Click
    Dim li1 As ListItem
    Dim addList As New List(Of ListItem)

    If (ListBox1.SelectedIndex < 0) Then 'No user selected
        MsgBox("Please select a user to add from the Listbox on the left.", vbCritical, "ListBox2 Validation Error")
    Else
        For Each li1 In ListBox1.Items
            If li1.Selected = True Then
                adduser(li1.Selected.ToString, intKL)
            End If
        Next
    End If
End Sub

Items are cleared and added using:

ListBox2.Items.Clear()

and

While SQLdr.Read()
            If SQLdr.Item(0).ToString <> "" And SQLdr.Item(1).ToString <> "" Then
                ListBox2.Items.Add(SQLdr.Item(1).ToString & " - " & SQLdr.Item(0).ToString)
            End If
        End While

Updates are happening on the load of a dropdownbox

This has something to do with autopostbacks and the page load I think, can someone please help

When I click the add button even if I have selected an item in the listbox, it will always return an error message. I don’t think the listbox changedselected item is firing.

Answer 1

Thanks kolin, your comment really helped.

The problem was that I was populating the listbox on dropbox1_load subroutine and hence everytime a postback was made the listbox would repopulate and no selection could every be made. SelectedItem would revert to -1.