Arccw weapons wont work?

I put the weapons in the addons folder and created a shipment and i can spawn the gun in the game without buying it from a gun dealer when i buy it from a gun dealer i get this error?

[ERROR] gamemodes/darkrp/entities/entities/spawned_weapon/init.lua:13: Tried to use a NULL physics object!

  1. Wake - [C]:-1
  2. unknown - gamemodes/darkrp/entities/entities/spawned_weapon/init.lua:13
    3. Spawn - [C]:-1
    4. callback - gamemodes/darkrp/gamemode/modules/base/sv_purchasing.lua:85
    5. callback - gamemodes/darkrp/gamemode/modules/chat/sv_chat.lua:17
    6. unknown - gamemodes/darkrp/gamemode/modules/chat/sv_chat.lua:325
    7. unknown - lua/includes/modules/concommand.lua:54

It seems that your weapon has no physics or is invalid. You should look for another one.