This is waaaay too simple to be failing ...
The circuit is composed of the following items connected in series:
12VDC voltage source (battery)
Output 16 acting as a switch
Strobe Light
Close Output 16 and the strobe should activate. If it does not, then either the circuit is not as described, the strobe's polarity is reversed, the battery is wonky, there's a faulty wire, or all of the above.