WSUS Server can not show more than 11 computers in one group

Hi,
I have WUSU running on our network. I have two computers groups and one
server group. Group A has 9 computers, Group B has 34 computers and sever
group has 9 server. Group A and Server group are working fine they are
showing all computers and group memebsers are receiving all updatetes. I am
very happy about it.
But group B which has 34 computers only 11 are showing. The computers which
are not showing have client installed version 5.8 and they have all latest
updates installed, it means they are getting updates from server but they are
not showing under computers on WSUS server.
I see some computer name change, some new computers show up but my server
can not dispaly more than 11 computers in Group B. Any suggestions please.

Younis George