URL parameters to pre populate a form

URL parameters to pre populate a form

Hi

Have tried to pre poulate a form from this...



to this..



Product_Used is a Lookup field to another table, with values 1,2,3...etc

Have tried the form url with "/Product_Used=2" or "?Product_Used=2" appended to the url, but that does not seem to work.  Have also tried ui.add restrictions, but that dis not work.

Cannot find anything on the forums. Can anyone help, going slightly mad as I am probably making a basic mistake?