Oledbexception не обработано

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If Me.DataGridView5.Rows.Count > 0 Then
           If Me.DataGridView5.SelectedRows.Count > 0 Then
               Dim intStdID As String = Me.DataGridView5.SelectedRows(0).Cells(0).Value
               'open connection
               If DataGridView5.Rows.Count = 0 AndAlso DataGridView5.SelectedCells.Count = 0 Then
                   MsgBox("Please select an Account to disable", MsgBoxStyle.Exclamation)
                   Exit Sub
               End If
               If Not cnn.State = ConnectionState.Open Then
                   cnn.Open()
               End If
               'delete data
               Dim cmd As New OleDb.OleDbCommand
               cmd.Connection = cnn
               cmd.CommandText = "DELETE FROM AccAdmin WHERE Username=" & intStdID
               cmd.ExecuteNonQuery()
               'refresh data
               Me.RefreshData()

               'close connection
               cnn.Close()
           End If
       End If

Что я уже пробовал:

Я получаю проблему нет значения для одного или нескольких обязательных параметров

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