.Mac and IMAP not working with iPhone

[davesaccounts]

I cannot, for the life of me, get my .Mac account's IMAP feature to synch with my iPhone.

If someone sends an e-mail to my .Mac address, I get it in both my Mac Mail on my iMac and on the iPhone -- just as you would expect. But if I delete it on either, it still remains on the other, until I manually delete it.

I have gone into advanced settings on the mail on the iPhone and aped a friend's settings. His IMAP works fine.

ARGH! Help!

Thanks!