The front panel is black because the U32 Pane Color 2 control default value is 0 (which correspond to color black ). Probably you used a numeric control, replace it with a color box control and click on it to set it to the color that you want (you can find it in the numeric control palette). Alternatively you can replace this control by a color constant in the diagram. Note that if you have LabVIEW 2009 you just have to copy the picture (snippet) in a blank diagram and it will generate the code and controls.
Ben