Making fields mandatory on the Sales Header.

In Sales orders of navision, Responsibility center field is the mandatory field and with out entering this field , if we move the Invoicing tab then error message should display that “Need to enter Responsibility Center in General Tab of sales order”. where should i write code and what should be written. Pls suggest the solution.

There aren’t straightforward methods in NAV to make a field mandatory (as concept from the begining was to allow to enter as little data as possible) - but this theme has been discussed here in forum many times, please do some search on “Mandatory” or “Default” and you’ll get plenty of info how it can still be done.