It sounds like it's setting on the anti-dryfire. Put the safety in the fire position and pull the string up until it clicks and then put the safety back to the "safe" position. Load your arrow and shoot as you always do.
Mine starting doing that this fall too, bow is 3 years old. We basically did what arrowhead said..my only complaint is having to do it at O'dark 30 at the base of the tree to cock it before I climbed up...but all in all that day worked out OK
"Only takes a second to change your season" Dad, 1980