RaiseError Didn't Raise Error Enough?

Why the error does not appear at the UI layer? I am using ExecuteScaler

BEGIN CATCH
PRINT N'The transaction is in an uncommittable state. Rolling back transaction.'
ROLLBACK TRANSACTION;
DECLARE @ErrorMessage NVARCHAR(4000);
DECLARE @ErrorSeverity INT;
DECLARE @ErrorState INT;
SELECT @ErrorMessage = ERROR_MESSAGE(),
@ErrorSeverity = ERROR_SEVERITY(),
@ErrorState = ERROR_STATE();
RAISERROR (@ErrorMessage,
@ErrorSeverity,
@ErrorState);
END CATCH