HI everyone, I need help!

Hi, I’m new on this forum and I’m in need of some help.

I have to stop an animation in which I explore an Image with a mask layer. The idea is that when I click the mouse, the image stop where it is so I can see what is there without problems, how can I do that?
I’ve tried with
onClipEvent(mouseDown){stop();} and
onClipEvent(mouseDown){_root.stop();} and
onClipEvent(mouseDown){this.stop();}

but it didn’t work, can someone help me?

-sorry for my english :)-