I have knitted all the surfaces together aside from the purple surface

I am now trying to knit the side purple colored surface together but will not let me. I've loosened the gap tolerance and unlock merge entities but still no success.

I when I to continue by lofting the bottom side panel, adding the guide curves immediately cause the loft to fail.

Have I attached my file to see if somebody to have a look and fix this problem.

Also with only knitted (non colored surfaces), I am also able to shell it regardless if I loosen the gap tolerance or shell it inwards or outwards.