Duration setting won't stick for Action?

Hi. I have an image that I would like to scale slowly (maybe 10 seconds). When I click on it and use the Scale slider (under Actions), no matter where I move the slider, when I use Preview or Play, the image always scales at 1.0 seconds. Also, when I Play the animation, and then go back to adjust the settings, the slider has gone back to 1.0 seconds, even though I double check everytime that the slider is set higher. Any help on this? Thanks in advance!