You didn't give us a lot of information so I will have to do quite a bit of guessing.
I'm assuming you have a layout that's based on a table. Let's call that table "Parent".
Then you have a related table as a portal, let's call it "Child".
In the settings for the relationship you need to check the "Allow creation of records via this relationship" on the Child side of the relationship.
To edit these settings go to: File - Manage - Database
Then choose the third tab "Relationships" and double clik on the [=] sign on the relationship line between "Parent" and "Child"