Thanks for that reply, Darrel. I see from your comments now why it wasn't working.
Since I was running Proteus Lite 6.7 and Labcenter doesn't support it anymore, they sold me the Proteus VSM Starter Design Kit (SDK) for their special price of $125. This will at least let me thoroughly evaluate ISIS for all my schematic work and will also at least let me do some simulations for the three MCUs that the SDK supports. I already have it running and have been running and looking at some of the samples to see how the VSM works. Looks like it may be a big help if I later decide to spend the $ and upgrade to the full 18F version of VSM. Since they credit the $125 towards the 18F version it makes is almost affordable.
Which Proteus versions do you use? I tend to use 18F version MCUs so I hope that if I do upgrade that the 18F version is all I would need....your opinion as to whether it would be worth it?
John