webmail Doesn't work with Plesk 8.1

[Dejin]

Hello,
Few hours ago I just had my server reinstalled.
I was using Plesk 7.6.1, after reinstalling OS I had Plesk 8.1
But I can't access webmail. When I write webmail.domain.com it says;

SERVER NOT FOUND!

I can see in DNS settings that there is webmail.domain.com!
None of the domain's webmail is accessible!

Have any suggestions?

Thanks in advance!