Help reconnecting display cable

I'm trying to replace the LCD + digitizer. The actual replacement went OK, but I can't reconnect the very small flat cable that connects the new display to the motherboard, the part that makes the screen respond to touch. It will not stay connected. I've watched other guides very closely and it seems that the connecting piece on the motherboard is "flush" with the heatsink (the part covered with copper), but mine is set back a small ways, about 1-2mm. I also didn't get replacement yelow sticky tape on the replacement screen. I don't know if that's causing the problem. Any ideas? Does it need to be stuck down or something like that?

This is the cable I'm referring to:

https://d3nevzfk7ii3be.cloudfront.net/ig...