@Ichiro: I checked your c_disc files above and noticed following two points:

1) Each end of lines of the c_disc.obj seems to be UNIX-style LF(ASCII:10) code.
My OBJ2MDL can correctly work if each lines of OBJ and MTL end with WINDOWS-style CR+LF(ASCII:13+10) codes.

2) Filename of OBJ and MTL contains "_".
"_" in the filename is used for loading multiple OBJs. So otherwise it should not to be contained.

I think those two are causes of the problem above. So it should be solved by:
1) converting ends of lines of the c_disc.obj to CR+LF. (by using suitable text editor with CR+LF save mode)
2) renameing OBJ and MTL file names without "_". (for example: cdisc.obj and cdisc.mtl)

And I will add those points to the Readme.txt of the next version of my OBJ2MDL.