Windsheild install not going so good

[TugOwar]

Trying to install new windsheild with new gasket, following instructions layed out by GMC Paul here.

I can get the gasket inside the lip at the top, around both top corners and part way down each side. The the instructions say to continue from the bottom center and work toward the lower corners, but I can't get the windsheild close enough to the cab for the gasket lip to catch on the inside.
What am I doing wrong? All help appreciated.