Advancing/Backtracking in Flash

Hey all, I know this may sound like a simple fix, but I just can’t seem to get it working. I currently have a photo slide show that has an empty movie clip controlling its advancing/backtracking functions, much like a glorified PowerPoint. Basically I need to have the buttons do the walking/advancing/backtrack through the slide show. As is, the buttons usually advance too much, because the function calls for an isDown call out.

Here is the mc code:
onClipEvent (mouseUp) {
_root.jungle_movie.nextFrame();
}
onClipEvent (enterFrame) {
if (Key.isDown(Key.SPACE) || Key.isDown(Key.UP) || Key.isDown(Key.ENTER) || Key.isDown(Key.RIGHT)) {
_root.jungle_movie.nextFrame();
}
}
onClipEvent (enterFrame) {
if (Key.isDown(Key.BACKSPACE) || Key.isDown(Key.DOWN) || Key.isDown(Key.LEFT)) {
_root.jungle_movie.prevFrame();
}
}

The movie clip is call Jungle_movie, and pressing right mouse, or SPACE, UP, ENTER and RIGHT advances, where as BACKSPACE, DOWN, LEFT make the slide show go back a frame. Is there a way to do this without the slide show advancing to many frames. Like using an onRelease method of AS?

Thanks for any help,
Jonathan