SSRS Parameter "SELECT ALL" only picks the first choice

So I've got a parameter for selecting the "Group".

It is a list of specified values. A,B,C,D,E,F,G and H.

I can select each one individually and it works great. But when I select "Select All" it will only show rows associated with Group "A".

I tried this article http://msdn.microsoft.com/en-us/library/aa337292.aspx and changed my filter expression from "Field.Group = @Group" to "Field.Group In @Group" but that produces the same results.

Any ideas?