before mounting the sticky helmet mount (i hope you used the curved helmet mount and not the flat mount)
clean the spot with some rubbing alcohol/roughen it up with some sandpaper...
then apply mount at roomtemperature and press it on for at least 5 minutes, then let it cure for at least 24 hours, applying pressure every now and then.... (still at room temp !)
the thing should be quite bombproof by then ....
if that doesnt work, the headband works great on helmets, i used to give it to friends who dont have a mount on their helmet and it works great !
and last resort => chesty mount ?
Belgium represent !
Once You drop in, it's all "Hakuna Matata" !
"The windows are vertical how am i going to poop on those?"-Killabees
"God isn't black, you fucking moron!"-Shibby
"I shit rainbows and sneeze glitter."-Arabian