In Sales Order Doc. i want that the Delivery date of two Sales Orders should not be same.
While generating New Sales Order the Doc. Delivery Date should not pick same date of any Sales Order given before.
I have a Sales Order with No. 1234 & Del. Date 30-03-10
If i create a new Sales Order with No. 5768 and if by mistake i fill same delivery date as given above, then it should occurs error as date not available or this date already exists.