Problem adding new record via subform

[topgeek]

I've got a simple training database that has three tables:

tblCourse
tblAttend
tblEmployees

I have a main form which displays employee information and the subform displays the courses they have attended. Whenever I try an add a new record to the subform for any employee I get an error message:

"Field cannot be updated"

The subform properties are set to edit so I can't see why I can't add anew record?

I'd be grateful for any assistance!!

Best Regards

 

[earthandfire]

This could either be something to do with relationships, or with the fields thatyou have on the some form (ie if they come from more than one table)