>I always regsvr32 /u and re-apply on my server - just in case. This appears to make no difference on this development workstation. I have rebuilt the project and regenerated the component ID - no change in adding this extra function!

Ok Andrew, here's another shot...
It sounds like maybe your re-registering your DLL ontop of the existing one? If so, trying un-installing the existing DLL and temporarily removing it from system all together. Make sure the app errors out that its missing, then regsvr the new one. Good Luck.