I believe I had the same issue John. The way i solved it (and this solution is posted somewhere here on these forums, but you'll have to dig):
In the triggers section add the following 2 triggers:
1. "Based on session variable value"--
If the value of the session variable VisitorIsMember is = a value of 1. (where VisitorIsMember is the name of my variable that determines valid membership upon login)
AND
2. "Number of items with a specific column value"--
If the total number of items where CatID has a value of 12 is > a value of 0. (where CatID=12, in my case, is all products that fall in the Training Manuals category)
Then in the calculations section use "based on items with a specific value":
total of Totalprice Where CatID has a value of 12 [times] 0.10
(depending on your discount, the '0.10' value will vary. In my case it's actually 0.1739, because members get $20 off the full price $115)
Hope this helps.
