Cross compile for nanox

i want to port a game of SDL and must use cross-compiler.
I have cross-compiled the sdl and the demos in the directory test for
nanox.
it’s ok.
but when cross-compiling the game,it failed:

it shows that:

undefined reference to 'GrOpen’
undefined reference to ‘GrDestroyWindow’

it seems that can’t found nano-x library.
but the demos in the directory test/ can be built.

thank you for any help…

Regards,
Andy