there is a bug or rather unfinished feature in darkbasicpro...
it means that you can't have levels in them which aren't in thier base.
so if you put it into the zip file (all pk3 are, are winzip 7.0+ specification compressed files) what you want the structure like is
\..\ << .bsp's here
\..\textures\ << texture directory sets
\..\scripts\ << in jk2 these are for icarus2 scripts, but q3 shaders
\..\shaders\ << not in q3 folders
\..\effects\ << jk2 shader fx's (similar to shaders, only more advanced)
\..\levelshots\ << level shot - not nessisary but good to have
\..\models\map_objects\ << level objects
\..\eagle\ << also not in Q3, this is for Icarus2 scripts - the eagle export
\..\strings\ << another not in Q3, used for the icarus2 scripting
usually for these in q3 and JK2 you'll see a directory called \..\maps\ - don't bother with it, as it WILL NOT work in DBP.
simply because Mike hasn't enabled the ability to load levels outside of the base directory. It's annoying, but its how it has to be unfortunately - everything else is in the right place.