Playback Keyboard using Sig

Hi,

I am trying to use the sig object so that if i press forward on my keyboard it plays forward but only until you let go and then i want the sound to stops, and then if i press back it plays back until i let go, almost like i am physically moving the playback with the keyboard keys. I have set it up but so far i can't seem to get the music to stop when i let go. Any ideas would be greatly appreciated.

Thanks