If the user doesn't highlight that's good proof that you either configured the address book wrong or did not add the right hostname-- otherwise mIRC would have properly highlighted the nick. Verify you set it up properly.
- argv on EFnet #mIRC - "Life is a pointer to an integer without a cast"
Found the problem. It seems (after reading help files and browsing internet again) that the order of appearance is crucial for getting it to work. When it gets a match on first hit then the rest stops, so i put my highlight group on top and now it works.