The sources allow these valid names:
const char *const standard_iwads[]=
{
"doom2f.wad",
"doom2.wad",
"plutonia.wad",
"tnt.wad",
"doom.wad",
"doom1.wad",
"doomu.wad", /* CPhipps - alow doomu.wad */
"freedoom.wad", /* wart@kobold.org: added freedoom for Fedora Extras */
};
So it should work.
Just make sure your file is and IWAD and not a PWAD.
Other option is modify the prboom_loader.c to pass the wad file as a parameter.
Also try to run your .CC after a hardware reset (turn off and on using the power switch) as if run after other application leads to failure.
In any case if you upload your .CC to Sendspace (I have problems with other servers) and PM me the link I can check the serial console for the error reported.
Regards.