When mIRC reports an error from a command where $& is used, the number of the line displayed is the line number where the command "finishes", it should be the line number where the command starts imo:
1| alias name {
2| drawcopy ... $&
3| .... $&
4| ....
5| }
mIRC would report an error on line 4 instead of 2 for that drawcopy command, a problem similar to
this problem I guess