[actionscript] Previous Frame

RightButt. onPress = functionality ()
nextFrame();
;

LeftButt. onPress = functionality ()
previousFrame();
; 

nextFrame works a goody. Whats the purpose for previousFrame as previousFrame lands on nothing at many. I am making use of actionscript 3. 0 i really believe.

prevFrame, http: //livedocs. adobe. com/flex/201/langref/flash/display/MovieClip. html#prevFrame().