Yep~ I found out what the problem is~
that is, since I have set a system variable statement like the following:
"MAYA_SCRIPT_PATH=c:\mayaptoject\mel" for execute my mel script, but, at the same time, mental ray will build another system variable statement :
"MAYA_SCRIPT_PATH=C:\AW\mental ray for Maya\scripts" where "C:\AW\mental ray for Maya\scripts" place all the mel script that mental ray create the attribute editor setting page for each light and material~ so, mental ray wrongly read my "c:\mayaproject\mel" as the path that it seek for building attribute editor... so.... HOHOHO.......... just cancel the "MAYA_SCRIPT_PATH=c:\mayaptoject\mel" then the problems of mental ray is gone!
