records within a portal are unique

[Steve Wright]

I have a table with a related table containing the following fields: the link field with the main table, the title and a miscellaneous field.

Through a portal I add more and more records to the related table. However, I do not want the same title to be allowed to be entered more than once in each portal.

It seems simple, but maybe i am too simple! I have tried creating a field that combines the link field id and the title and then validate it by uniqueness. It doesn't work.

Any help greatly appreciated.