Could not find the ColdFusion component or interface...

CF10 on IIS 7

I have a webservice set up that needs to be called from a remote server.  It is set to access="remote". It works fine when called from the local machine.  But calling it from a remote server fails.  I can perform an HTTP Get and pull down the WSDL from the remote machine, but when I attempt to invoke the web service remotely, I receive the "Could not find the ColdFusion component or interface...." error.  The incredibly odd thing is that if I intentionally break the CFC, outputing an undefined variable or something, the error is returned to the remote request!

• Is there some new setting that I must change to allow for remote invocations?
• This is on a PCI compliant subnet.  Could firewalls be blocking the CFC interaction?  Do CFC's return on a separate port or something?  Could the headers be blocked?