Provider 4.0 and 3.51 DB

Hiiiii all

I made programe was used ADO Control the provider was 4.0
to now all things are (NEW,UPDATE,DELETE)OK, But when changed to ADO provider 3.51 this message was appear
"insufficient key column for updating or refershing "
in updating action,But add new and other action no problem.
I was used Access97.

with regards