[racket] gl2d / gl-world: Debugging strange error / determining which libraries are missing

Hopefully someone out there can help me out, I've run into a a bit of
a problem with the gl2d and gl-world packages from PLaneT. I've got a
relatively small sample and whenever I run the code (even after
commenting out all of the OpenGL specific code other than the big-bang
call), I always get this error:

send: target is not an object: #f for method: call-as-current

The one relevant response I've found thus far on the subject is from
Matthew Flatt from last December on the mailing list (
http://lists.racket-lang.org/users/archive/2011-October/048813.html )
which says to check "Do you have "libgdkglext-x11-1.0" and
"libgtkglext-x11-1.0" installed?", which I do. There's a .so for each
in my /usr/lib directory. After that though, I'm not sure where to go.
Is there perhaps some way to check which libraries that Racket is
trying to load / what else might be causing the error?

Thanks,
JP