Help with Try... Catch and the Selected Value of a DropDownList

Hi Experts - I need help using the Try... catch block with my DropDownList Control.

The value of the drop down have recently changed and may no longer match the values in my database.  That being the case i wanted to set the SelectedValue for any non-matched items to the default value of "Unassigned".  Here's what I wrote:

'  Get the values for the dropdownlist
' -------------------------------------------------------------------------------
Dim MyBLL As New PickPackBLL()
Dim dt As DataTable = MyBLL.GetBinLocs()

ddOpp.DataSource = dt
ddOpp.DataTextField = "BinLoc"
ddOpp.DataValueField = "BinLoc"

'  Set the Selected Value of the drop down list.
' -------------------------------------------------------------------------------
Dim SelectedBinLoc As String
Dim defaultSelectedIndex As String = "Unassigned"

Dim pickTicketLogic As New PickPackItemsBLL()
Dim dtpick As DataTable = pickTicketLogic.GetPickTicketItems(hfPickTicketID.Value)

If dtpick.Rows.Count > 0 Then
    Dim row As DataRow = dtpick.Rows(0)
    SelectedBinLoc = row("BinLoc")
End If

Try
    ddOpp.SelectedValue = SelectedBinLoc
Catch ex As Exception
    ddOpp.SelectedValue = defaultSelectedIndex
End Try

ddOpp.DataBind()

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Even with the "Try" block in place I'm still getting the "'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items."

I was hoping that the try would catch that error and the move on to the exception block and useing the defaultSelectedIndex value.

Can you tell me what I'm doing wrong?

Thanks!