Error when trying to create a instance of a class on the network - DOTNET

Short story is this. I have a class that sits on a network share, and
a local windows form that references the class on the network. Both
the form and class are signed with the same SKN. I have added the SKN
to the .net framework and giving it full trust permissions. But when I
try to create a instance of the class, I get a error "Exception has
been thrown by the target of an invocation" with a inner exception of
"That assembly does not allow partially trusted callers." I even get
this error when running in debug. I just got a new PC that is windows
7 64bit, my previous machine was a windows XP 32bit and had no issues.
I have tried cleaning the solution, recompiling both the form and
class. Running VS as admin and nothing seems to work. Anyone have any
ideas?

Regards