Is it 3wire or 2wire? if it's 2 it's more than likely low voltage, can you tell what gauge it is?
Another thing that you might try is to get a tool called a toner and try to trace the lines. There may be a break in it. If your brave enough for it you can also disconnect the wires that you think go to those lights in the panel and start twisting the wires together int he junction boxes, then with a meter, set it to audible ohms and see if you get a tone out of the meter at the panel end of the wires you disconnected.
Another thing that you might try is to get a tool called a toner and try to trace the lines. There may be a break in it. If your brave enough for it you can also disconnect the wires that you think go to those lights in the panel and start twisting the wires together int he junction boxes, then with a meter, set it to audible ohms and see if you get a tone out of the meter at the panel end of the wires you disconnected.