I'm getting this weird error:
* $dll: unable to open 'D:\pre\functions.dll'
when using $dll(functions.dll,VisualToLogical,$1-)

The DLL is NOT in use!
I can use it from another computer (same file, I'm accessing it with my home network)

any ideas?

1) Have you tried copying the dll to your mIRC directory and
    trying it from there?
2) If using v6.12, are you sure the dll is compatible ?

1) the dll is in the mIRC directory
2) hmm it's not...
how do I convert it?
what are the changes in mIRC 6.12?

I've tested it on my computer with mIRC v6.12, it works
and on the other computer with mIRC v6.03.
still doesn't work :\

figured out what the problem was
it was a MFC DLL