Unity3d kongregate API Problem with Virtual Goods

I am trying to add microtransactions from the kongregate API. Please find my code below: public string[] cashTypes = new string[1] { "cash500" }; // Purchase CashItem $500,000 Application.ExternalCall("kongregate.mtx.purchaseItems", cashTypes, kongregateAPI.kreds += 500000);

You can find the API tutorial for it here - http://developers.kongregate.com/docs/client/purchaseItems

I believe I did everything correct internally. "It takes either an array of item identifiers" AKA cashTypes. The identifiers are used to recognize the items to purchase. So I added the array, which is cashTypes...

Thank you