If you have lsimagefolder already defined which it should be then it can not find the image...

Typical OTS2 Setup:
OTSMajorVersion "2"
OTSMinorVersion "0"
ThemeName "Do That Now!"
ThemeAuthor "howudodat"
ThemeVersion "0.1"
ConfigDir "$ThemeDir$config\"
LSImageFolder "$ThemeDir$images\"

So in theory you are loading your images from your theme images folder already!
So basically you just use "pl1.png" without root.