Can i add effects to a "gif" picture?

Hi everyone,
I have a “gif” image which is a “jpg” picture i converted into a “gif” format.
I imported it to my Flash clip. I want it to be transparent at the first frame of its timeline and to gradually show up as it reaches ending keyframe .
I converted that image to a symbol.
At its’ first timeline frame ,from “color” combo box in the “properties” area, i selected “alpha”. At the ending keyframe i selected “none” from the “color”
scrolling list in “properties” area.
Now i’m having a white page at the first frame and an image at the end keyfarame.
In order to make the image gradually show up i selected: “shape” from the
“Tween” scrolling list at the “properties” area.
I get a dashed line crossing the time line and the gradually showing up of the image is not working.
Can i have an advice of how i should do that ? Whats wrong with what i was doing ?

Thanks !

You want motion tween not shape tween.