max error message about shader

It is when I use the "43j-fourwaymix.jxs" shader located in the tut folder.

Sometimes Max tells me:

• error: — START GLSL INFO LOG: fp –
ERROR: 0:25: ‘output’ : Reserved word.
ERROR: 0:25: ‘output’ : syntax error parse error
ERROR: Parser found no code to compile in source strings.
• error: — END GLSL INFO LOG: fp –
• error: jit.gl.shader: GLSL program failed to compile.