Hi,
This is the second it has happened to me, both times I was puzzled. I'm trying connect two nodes in BizTalk 2006's Map Editor and can't: you get the “Deny Drop” icon. Solution: Check that there's no value in the target node, like a space !!!
Remove the value/space.
Dear Microsoft: Give feedback on the reason why we can't connect; a bubble or change the status bar message: Can't connect because the target element has a Value set.
Pat