Lumocolor pens come in permanent and non 
permanent.  I believe they were made specifically 
for overhead projectors, which is why they come 
in all sorts of colors and have permanent and non-
permanent.  Non-permanent wipes off, and you 
can't remove permanent unless you want to gouge 
out the lines.  Guess which kind you have?  ^_^  
Try getting the perm kind, it'll go easier for 
you.