DEA6.0 - Mobile app - Save doc problem

I used Domino Designer to build a simple application, the main form is Contact, it contains two editable fields “Name” and “Addr”.It seems that the standard code of “Save” button never works:

@URLOpen(“{$session}R=SD{$context}&F=Contact”)

I tried to use:

@URLOpen(“{$session}R=SD{$context}&N={$document}&T=Edit”)

It is working for new document only, and also automaticly change Form value to “Demo”. (the Form should be “Contact” by default)

Anyone help?

Thanks.