.NET 2005 TRY..CATCH With SQL RAISERROR Not Catching

Is there a reason why the following code does not raise an error in my .NET 2005 application? Basically I have a try..catch in my stored procedure. Then I have a try...catch in my .NET application that I want to display the error message.

But, when the stored proc raisses the error, the .net code doesn't raise it's error. The .NET code DOES raise an error if I remove the try..catch from the SQL proc and let it error (no error handling), but not if I catch the error and then use RAISERROR to bubble-up the error to .NET app. (I really need to catch the error in my SQL proc and rollback the transaction before I raise the error up to my .NET app...)

SQL

BEGIN TRYBEGIN TRANSACTION trnName

DO MY STUFF....  <---- Error raisedCOMMIT TRANSACTION trnName

END TRY

BEGIN CATCHROLLBACK TRANSACTION trnName

RAISERROR('There was an error',10,1)

 

END CATCH

ASP.NET CODE (No error raised)

Try

daAdapter.SelectCommand.ExecuteNonQuery()Catch ex As SqlException

Err.Raise(50001, "ProcName", "Error:" + ex.Message)

End Try