Possible oiling concerns

Can anyone tell me why my rockershaft won’t sit in the posts?????? I’ve been trying for half an hour now I think and it just WONT SIT IN! It’s 100 degrees out and this thing is being a giant pain in the *** and I literally can’t find any reason why! The rockers aren’t between the shaft and the posts. There’s no tension between the valve-rocker-pushrod connections that could pry it up. It just won’t go in after the rockers have been out on