reading that many markers, off the disk, apart from anything else, is going to be a bit slower.
You would be best off doing
net.SetMarker('cs'&m#,-lat$,lon$,'~MapPinBlue.ico')
and then adding MapPinBlue.Ico to the solution.
That said, I'll continue to investigate why the call to load the icon off disk is failing.
cheers
Bruce