Exception in Try Catch is NOTHING

Really don't know why this and other similar piece开发者_开发技巧s of code are not working in my MVC3 application.

  Try
        Dim x As Integer = 0
        Dim b As Integer = 15 / x
    Catch ex As Exception
        Debug.WriteLine("aaa" & ex.Message)
    End Try

simply ex is ever nothing. i tried debugging, the debugger enter the catch clause, the VS popup show me the correct exception values... but hovering ex with mouse show it is nothing. the debug immediate window show the correct message "aaaOverflow arythmetic operation...."

really i'm going crazy!

There is an object called Err. Err.Description contains the message error. I had the same problem and Err saved