I'm wondering how to add a second item to the cost of a deployment.  So say "Shock"
I'm trying to use the following, but it keeps deleting stuff down to once item type for cost.:  Can you please tell me what i'm doing incorrectly?  
Thanks

"Costs": [
        {
          "Amount": 2,
          "Shortname": "grenade.beancan"
        },
        {
          "Amount": 2,
          "Shortname": "grenade.f1"
        }
      ],

thank you