Compositing Problem

Hi- I have a video that has an alpha channel and within it a craphic element that opens up containing a blue screen. In the blue screen I've placed a graphic in a layer behind and keyed it to that blue so it shows through, but I'm also trying to place a still image as a backround to the whole thing. The still shows through the transparency fine until the graphic opens and the blue screen shows up, then the backround still goes away and turns black. What am I doing wrong? Any sugestions? Thanks in advance.