It's possible that the fitting itself is bad. I changed mine out for a 90° fitting so it's easier to get on it.
It also maybe dried up solid in the hole of the bolt. In this case I'd pull the bolt, remove the fitting and clean out the hole.
And/or you may have to lift the coach up by the frame to unload the suspension so the grease can escape from the hole to the bushing.
*Current: 2005 Ford F350 Crew Cab Dually 6.0 diesel 4x4*
*Retired: 1987 F350 Crew Cab Dually 6.9 turbo diesel
2007 Forest River WildCat 32QBBS