How do I get a Compile error from NVIDIA CG?

Question

How do I get detailed errors from a cg compile?

At the moment my code is something like:

prog = cgCreateProgramFromFile(
    context,
    CG_SOURCE,
    filename,
    proifile,
    null,null);
std::cout << cgGetErrorString(cgGetError());

But all I get is "The compile returned an error."

Is there any way to get a more involved error message, like glGetShaderiv with GL_COMPILE_STATUS for opengl shaders?

Can't find anything in the reference but is seems like a fairly basic requirement.

I am running cgc on the shaders first with no code generation to check for errors but that doesn't catch everything.

Thanks.