avconv issue: cannot stream track different than 1st (5 tracks in original video)

Question

I am trying to restream - transcode using avconv, the code below is working fine, the only issue is that I cannot use a different track. I tried -ac 2 or -ac 5 but these doesn't seem to work. Any idea?

Please find my sample code below:

avconv -i http://udpproxy.stream.tk:8070/udp/239.254.1.111:1234 \
 -vcodec libx264 \
 -profile:v baseline \
 -preset veryfast \
 -filter:v yadif \
 -trellis 2 \
 -async 1 \
 -pix_fmt yuv420p \
 -s 1280x720 \
 -r 25 \
 -g 25 \
 -bf 2 \
 -b_strategy 1 \
 -keyint_min 25 \
 -crf 20 \
 -b:v 1200k \
 -minrate 2000k \
 -maxrate 4096k \
 -bufsize 2048k \
 -threads 4 \
 -acodec libvo_aacenc \
 -ar 48000 \
 -ab 128k \
 -ac 2 \
 -f flv \
 -metadata service_name=streamtv \
 rtmp://192.168.207.11/locked/streamtv \
> /home/streamer/logs/streamtv-"$DATE".log 2>&1 & echo streamtv transcoding initiated