Heat Rave R

I managed to get my hands on one of those rare targa roof bands and have installed it. However, it seems like I can't get the rearward edge to latch onto the plastic fittings. I've been banging on it all afternoon and it just keeps popping up. I can't tell if it's getting under the edge and just not catching, or if it just isn't streatching far enough apart to even get under the edge. If I pull open the metal edge of the band, I'm worried it'll be too loose. Even with only the front edge hooked, it does seem secure, but I'm just worried if it'll fly off the car at high speed if I don't figure out to get the back edge latched. Anyone else with the band have this problem.