I just bought a Break-Barrel Powerline 1000S Daisy air rifle (1000 f.p.s., .177 caliber) because it is supposed to be a great entry-level powerful air-rifle for short distance plinking. However; when I got it home, I found that I could NOT cock it. Do they come with some sort of lock on them in the box to prevent cocking. I've read the instructions and can find nothing about it. I've tried to pull the barrel down to cock it per the instructions, but it will NOT. Any ideas? Thanks.