bubba is right, I've seen that before with the single trigger,, easy fix.
The install is goofed up,.
Take the barrel out, then relax the hammer and take the lock out.
Then take the trigger out.
Clean and oil everything.
Look at and function the lock out of the stock.
Look at how the trigger works, out of the stock. (is the little wire return spring there?)
Install the lock in the half-cock position.
THEN install the trigger,,