To make field mandatory in BP master

Hi All,

I have written the below query in Sp_SBO_SP_TransactionNotification to make one of the tax information field mandatory

IF @transaction_type IN (N'A', N'U') AND (@Object_type = N'2')

BEGIN

declare @n varchar

SELECT @n = T1.TaxId0 FROM ocrd T0 inner join crd7 T1 on

T1.cardcode=T0.cardcode where

T0.cardcode = @list_of_cols_val_tab_del AND

((T1.TaxId0 is not null))

IF (ISNULL(@n, 0) = 0)

BEGIN

SET @error = 10

SET @error_message = N'PlsNo'

end

END

Please help where am i going wrong.

Thanks In Advance

Regards,

Kanishka