Finding related records -- Really puzzled

[Hiroshi]

Hello,

I was wondering if someone could help me out with something that might be very elementary.

I have a database of teachers each with unique IDs which I regularly delete and repopulate from data on our server.

There are a couple of flags that I place on my end on FMP which I want to store on a related file with the IDs as the matching field.

I pretty sure I've set up the relationship properly because I can click on the checkboxes on the main file and the related checkbox in the related file checks on.

But, when I try to find records with the related checkbox checked "on" on the main file, I get a message telling me that "one or more of the relationships are invalid."

What could this be?

Thank you in advance for your help.

Hiroshi

PS I posted this earlier in the relationships forum, but perhaps it was off topic there.