HBS Not Working? or Glitch?

Hey Guys I Wanted to try out the Heartbeat, but when i bought 1 it showed a error, so i bought another 1 and it said a error, here's a picture of wat i mean

Do you already have an item equipped that uses a battery?

what happened to ur guys head??.........and wat he said (thaton3guy or w/e) u mite hav anothr battery item equiped to u.
iff u dont it must be a glitch maybe u should try l8r

lol wats other Batterie i got epuiped, I only got Ump,flash,grenade, and that's it