I believe there is a problem with the “pre-converted” (from MOM 2005) management
pack that is offered for BizTalk 2006 on the SCOM 2007 management pack download
page.
I believe the conversion started with the BizTalk 2006 (flat) MOM 2005 management
pack, rather than the BizTalk 2006 R2 version. The latter is available here.
Assuming you have already installed the MOM
2005 Backward Compatibility Management Pack, version 6.0.5000.12, you should
be able to import the 2006 R2 version (via the Operations Manager Migration Wizard.)
The reason this is important is because the computer attribute that the (older) management
pack is looking for includes:
MatchWildcard(AttributeValue(BizTalkServer2006Attribute), "3.5.*")
BizTalk 2006 R2 has a version stamp of 3.6.1404.0.
(I believe other
folks have run into this issue as well.)