Podcasts disappear after sync

Can someone please help me with this?

I have an iphone with OS 3.1
Everything else on the phone is working fine, except for the podcasts.
I put them all manually. All auto sync in unchecked.
But when i sync my iphone, all the podcasts i've put there disappears.
That happens every time i hit sync.

Is there a fix for this?

Thank you in advance.

About the only reason I can think of is that the sync option is not checked.