Simple Databinding Question

That I cant figure out.

I am creating a front end for a school database that has about 40 Different Tables. Each table has a common Student Id # and Family Id # Etc..

Currently I am setting up the Family info for the student.
Family Table = TblFamily
Student Table = TblStudent
Family ID # = FamilyID

What I need is when I select a student it Automagicly changes the Family Id for the Family Table.
I have fallowed the instructions from the book I have, as well as a lot of online tutorials and each time i get the same error message "unable to find "FamilyId" in datasource".

thanks
Mike C

It's difficult for us to say what's wrong only with this info...

The error says that the FamilyID don't exists in the datasoure...