how to use mencoder as external encoder of virtualdub?

this is my settings below

audio:
-ovc frameno -of rawaudio -af volnorm -oac faac -faacopts br=32:mpeg=4:object=2 -srate 22050 - -o "%(tempaudiofile)"

video:
-nosound -of rawvideo -ofps %(fpsnum)/%(fpsden) -vf harddup,pp=md/lb,scale=%(width):%(height) -ovc x264 -ffourcc H264 -x264encopts crf=24:threads=2:bframes=2:level_idc=21:nopsnr:nos sim -af volnorm - -o "%(tempvideofile)"

multiplexer:
-add "%(tempvideofile)" -add "%(tempaudiofile)" "%(outputname)" -fps %(fps)

But it don't work, and give some error message "Cannot seek backward in linear streams! Seek failed" in log,

I don't know how to solve this problem,please give me some help,thanks