Trouble with a Gun

[Dealaman]

I know this isn't about a mag, but I don't know where else to get help. I sent this guy a Piranha STS G2 and stuff and he traded me a nitro tank. He says the gun doesn't work and it has worked perfectly for me every time I shot it. I told him a bunch of things it might be, but do you guys know what it could be? Cup valve maybe? Thanks

Carson

[Dealaman]

Ya

He says it just sputters and wont shoot.

[PyRo]

Is his tank full?

[Dealaman]

NM

I fixed it.