Active Directory and Nested Groups

System

TeamSite 6.1 on W2k SP4

I'm having a bit of a problem with nested domain groups (active directory). I've read a few posts about similar issues and have read the "Interwoven Best Practices TeamSite and Active Directory" PDF. According to the PDF, what I want to do is possible.

Here's the scenario:
I have a branch shared by domain group pge\groupa. Group pge\groupa has 2 members: pge\usera, pge\groupb. groupb has 5 users in it and no groups. I create a workarea "load" and share it with pge\groupa. The owner of the workare has no problems with it, but the members of groupb can only access the workarea, but have no write privileges. In fact, the message I get when trying to edit a file is: Not a writable workarea: //SERVER/default/main/BRANCHNAME/WORKAREA/load

I've tried this same scenario a couple of times. Same results. Also, I've looked at the OS level permissions and they look right. Full access to pge\groupa.

Thanks in advance,

Jason