The problem is that OR is an operator that takes two boolean arguments and returns returns one.
So in your case, the 1 OR 3 OR 4 part really executes as two separate subexpressions:
(1 OR 3)
(result) OR 4)
What you need to do is something more like this:
if ddlCollType.SelectedItem.Value = 1 OR
ddlCollType.SelectedItem.Value = 3 OR
ddlCollType.SelectedItem.Value = 4 Then
You might also want to look at select statements.