I'm sorry, I've never used glPathGlyphsNV.
But If you get errors like "GL_INVALID_ENUM" or "GL_INVALID_VALUE" or "GL_INVALID_OPERATION", the chance is VERY high, that the xml docs for these functions give you hint, on what you might have done wrong:
http://developer.download.nvidia.com/assets/gamedev/files/GL_NV_path_rendering.txtsearch for "GL_INVALID_OPERATION", and it will give you this information:
- Queries (glGetPathParameteriv, etc.) allowing only a single path
object to be specified, generate a GL_INVALID_OPERATION error
if the path name does not exist. - glWeightPaths, glInterpolatePathsNV, and glCopyPathNV generate
a GL_INVALID_OPERATION error if any of the named source paths
do not exist. - Path commands that modify the commands, coordinates, or parameters
of existing path objects (as opposed to specifying a path object
completely) generate a GL_INVALID_OPERATION error if the path
name does not exist. - When there is also a /numCoords/ parameter,
the GL_INVALID_OPERATION error is generated if the number of
coordinates is not equal to the number of coordinates needed by
the command's specified path command sequence. This provides
a sanity check.