lots of bugfixing for lookupgrid

Controls.LookupGrid/frmLookupGrid.vb

@@ -17,6 +17,7 @@ Public Class frmLookupGrid
         view = viewLookup
         grid = gridLookup
 
+
         If DataSource Is Nothing Then
             Exit Sub
         End If
@@ -136,7 +137,7 @@ Public Class frmLookupGrid
     End Sub
 
     Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
-        SelectedValues.Clear()
+        SelectedValues = New List(Of String)
 
         DialogResult = DialogResult.Cancel
         Close()