Need help with lvl bar

I am porting my game to flash and have got a bug with the lvl bar.
I have quite a complicated event that increases the lvl bar in a nice way, but it bugs out on Flash.
So now I am trying to make a simpler version that should just set the xwidth of a level bar according to its current lvl and its max level.
At its max level the bar should be full. When for example the max lvl value is 15, and the current lvl value is 7 it should be half filled. After it lvl up the max lvl will increase, to say 25, so then when at lvl value 7 it would not be as filled up, and so on and so on.. I hope this make sense?

I have attached the example. The top lvl bar will work in the mfa, it is just that it breaks in flash, so it is the bottom lvl bar I want to have a simpler method on that could work in Flash. (Or if it is possible to modify the top bar to work in Flash) Could anyone help me please? :)