Typical behavior under stress -- he was working the lever, but not squeezing the trigger and didn't realize he never fired a shot.
During the Civil War, Ordnance scoured the battlefields, picking up and refurbishing abandoned muskets. A common comment in an Ordnance officer's report is the number of abandoned muskets with two to as many as 12 charges in the barrel. Under stress, a soldier would go through the motions of loading, but forget to put the cap on. He would snap the trigger, and not realizing the weapon hadn't fired, would reload.