How users move between records?

>While a user is on a form, how can I programically know when they have moved to a new record? I've tried storing the RECNO() in a variable (see below) and then update it through the REFRESH method but haven't been successful, yet.
>
>lnLastRecNo = RECNO()
>lnCurrentRecNo = RECNO()
>
>
>Thanks,
>Robert