After some time the enemies don't receive or deal damage

Hello! I made a gun and an AI.The AI can damage me and I can damage it back. But after some time i don’t deal any damage.
The character: http://imgur.com/a/1sTHr
Sword damage: http://imgur.com/a/xuxz4 and http://imgur.com/a/WfPIa
Ai getting damage: http://imgur.com/a/GbXAd
Ai dealing damage: http://imgur.com/a/Szzt9

Thank you in advance!
Edit: Found out that this happens exactly 1 minute after starting to play.