Hello All

I have a sony car head unit which i connect to my nexus 7 tablet via bluetooth, this enables me to stream music from
my tablet to the headunit, i can change the track, pause rewind etc from the headunit but i cant seem to change to a folder or example go up a  folder or down

Does any one know if this is possible? is there a specific music app i need to download for the nexus 7
If i have  mp3 cd i can change folders but it wont seem to let me do this when streaming via the tablet