Should this be working ? (string.Format() )

This code works in VS but not in SE.

public static void SetRotorAngle(string name, double angle, double velocity)
{
Echo(string.Format("SetRotorAngle : name={0} : angle={1} : velocity={2}", name, angle, velocity));

...
}

"An object reference is required for non-static fields method or property for Sandbox.ModAPI.InGame.MyGridProgram.Echo.get"

I have seen lists and all sorts of things work in online tutorials, but they are very hit and miss for me - I am doing something wrong,...

Should this be working ? (string.Format() )