Alpha Trooper XD always jamming/darts problem

Hey guys,

So this is my first post on here. I have recently bought the Alpha Trooper mission kit, and when I fire it, 90 percent of the time, the darts jam. Is this normal? Ii found out that the darts it came it have a the T letter code on it. And every time I fire the T letter code darts, it works, But with the other ones, no. Please help me, as I can't refund it, threw away the receipt!

Thanks