Mobileme mail doesn't sync; help!

I was using a free trial mobileme subscription and all my mail and calenders synced fine.

When I got a paid account, my mail won't sync.

I still get my emails, but when I mark them as "read" on my computer, they still show up as new messages on my iphone (the mail icon still shows the # of messages i had read on my computer as new on the iphone).

Any solutions? When I was using the free trial, it synced the mail fine (i.e. when I read it on my computer, it would automatically sync it and mark it as "read" on my iphone.