I assume that mapslist is a Basic4ppc ImageList. It looks to me like a problem with that. I've not looked at ImageList before and assumed it stored bitmap references. In fact it appears that it can store bitmaps as both string filenames and as bitmap references. As ImageList is not as separate control but is implemented by inline code in both the IDE and optimising compiler I can't be sure but it looks as though normally the IDE/compiler compensates for this but in your instance it may not be and is passing an image filename as a string to DrawImage - hence the complaint.
The above is my best guess unless you can post some code that displays this behaviour.
The above is my best guess unless you can post some code that displays this behaviour.