Air awning problem

Blade58

Hi everyone, i have bought a camptech starline 260 deluxe porch awning ,after sliding onto rail pegging corners and inflating i am left with a six inch gap between my van and the awning no amount of tugging ,pulling,moving poles etc seems to rectify it.my
van is a abi jubilee globetrotter 2 berth, can anyone help please . By the way just returned to touring after 25 years so maybe its me not up ro speed with things .

Dave.