Answer by Cherno

Orb gave you the explaination, I try to make it clearer to you. To solve your problem, it's important to know how your custom classes (Vitals etc) are defined. They should either be in the same script that uses them (if that's the only script that uses this type of class), OR have each one's code in a seperate script that _doesn't_ have the "uses MonoBehavior" part in the script's title. The latter one allows you to use your custom class in any other script.