can not record stereo audio

[TKooijmans]

When I use this
ADD 1 FILE "myfile 1.mp4" -codec:v libx264 -crf:v 23 -preset:v veryfast -filter:v format=pix_fmts=yuv420p,tinterlace=4 -flags:v +ildct+ilme -codec:a aac -b:a 128k -ar:a 48k

I get a mp4 file with 8 channels audio.

When I use this
ADD 1 FILE "myfile 1.mp4" -codec:v libx264 -crf:v 23 -preset:v veryfast -filter:v format=pix_fmts=yuv420p,tinterlace=4 -flags:v +ildct+ilme -codec:a aac -b:a 128k -ar:a 48k -filter:a pan=stereo| FL < FL + 0FC + 0BL + 0SL | FR < FR + 0FC + 0BR + 0SR

I should get a file with stereo audio, but there is no sound.
I only get silent audio.
Is there something changed?