Oki i'll try to explain
first as i'm french and my english is not so good here a picture to explain better

Now to make it run good i made the png at the exact size of the anim so 250x15 px
there are two png one for the Filled and one for the empty add them by the button "..."
Set like me
and be sure your object is set as an image and not a text.
If you want see by your self this setup gone since my last DXtheme on the System information object.