Problem?can you help, Please?

I have just converted a Microsoft Access V 2.0 to Access '97. Everything is fine except that I have a number of forms which contain subforms. When I have designed the subforms (Datasheet default) I have been able to simply use the <Enter> key to move through the fields across the page.

Problem: When I use the subform as in a mainform the <Enter> key fails to work and I have to <Tab> across. This never occurred in V 2.0.

I have gone in to the Options and keyboard and tried resetting everything but to no avail. What is going on?

Any help you can give would be greatly appreciated, Thanks