apparently your sear isn't catching sear slug. Okay do as doo-doo brown said. adjust your slug by putting a right size allen key down the hole which is at the top of your gun (you might need to pull or push your cocking rod slightly depending on what kind springs you got in there) and turn it clockwise a 90 degrees at once until it starts catching sear. Then turn it bit more (like 10-20 degrees).
You might need to re-time the gun after that, and there is possibility that the slug is so loose that you need to do this after shooting 500rnds. Had that problem, fixed it with loctite.
For timing and general cocker info check Ravi Chopras page at
http://www.paintballravi.com/Articles/AutocockerInfosheet/ACTroub.html
Okay, less obvious problems are that your searspring is broken (or lost), or your ram's screwed up.
You might need to re-time the gun after that, and there is possibility that the slug is so loose that you need to do this after shooting 500rnds. Had that problem, fixed it with loctite.
For timing and general cocker info check Ravi Chopras page at
http://www.paintballravi.com/Articles/AutocockerInfosheet/ACTroub.html
Okay, less obvious problems are that your searspring is broken (or lost), or your ram's screwed up.