unable to link mpeg lib

[leesongchen]

hi:
	i am making a project about mpeg.i choose mpeg_lib.
	but i can not link to the library 'libmpeg.so'.it does exist,and its
examples can link to it without any problem.

g++ -o qmpeg -L/usr/X11/lib -L/usr/qt/lib -L/usr/lib -lX11 -lXext -lqt -lmpeg \
	main.o qmpeg.o qcontrolpanel.o qmpeg.moc.o qcontrolpanel.moc.o 

qmpeg.o: In function `QMpeg::slotMpegPlay(void)':
/root/mpeg/mpeg/qmpeg.cpp:121: undefined reference to `SetMPEGOption(MPEGOptionEnum, int)'
/root/mpeg/mpeg/qmpeg.cpp:122: undefined reference to `OpenMPEG(_IO_FILE *, ImageDesc *)'
/root/mpeg/mpeg/qmpeg.cpp:151: undefined reference to `GetMPEGFrame(char *)'
/root/mpeg/mpeg/qmpeg.cpp:161: undefined reference to `CloseMPEG(void)'
collect2: ld returned 1 exit status
make: *** [qmpeg] Error 1

it seems as if i do not use " -lmpeg" option,but i DO.any suggestion?
(libmpeg.so installed in /usr/lib)