ECMA 2.0 "Extension could not be Instantiated"

Hi,

I have written an ECMA 2.0 MA in my dev environment. I'm using Visual Studio 2010 SP1 and have built the DLL for release. I then exported the MA so that I can import it into my test environment and copied the DLL to the FIM Extensions folder. When I import the MA, I get to the 'Select Extension DLL" dialogue and press refresh interfaces. I get an error pop up saying "The extension could not be instantiated".

I don't understand how to troubleshoot this. There doesn't seem to be anything meaningful in the event logs. Can anyone help me understand what's happening?

Lee.