How to add tanks to traders? [Please Help]

So I want to add tanks to my hero and bandit traders but when I try to they dont show up in the buy menu. I have followed all the tutorials I can and still they are fucking up.
I am using CfgServerTrader for my traders and this is how I have mine setup and they show up in trade menu with the trader:
class M1A1 {
type = "trade_any_vehicle";
buy[] = {10,"ItemBriefcase100oz"};
sell[] = {5,"ItemBriefcase100oz"};