make sure theres no dibris or sand in the end of the connector because that will cause it to never fully seat. as long as theres nothing in there, put a flat head screwdriver on the edge of the connector and try to get some good leverage on it and push it as hard as you can. you should hear a little click when the 2 connectors are fully seated.

I had similar trouble when I converted my old 96 hatch (the one I made the how-to with).