Don't see .NET function in Rule Composer - fact explorer

I created a .NET DLL that contians a couple of functions I will need to 
access from the BRE. I have built the .NET assembly and GAC'd it. I browse
to 
the assembly in the Facts Explorer. After referencing the DLL in the Facts

Explorer I can see the Class name (RuleFunctions), but I cannot see any of
my 
methods. Any idea what I've done wrong? Thanks.