override OnServerAddPlayer gives scripting error

OK, sometimes i just don’t understand what i am doing wrong…
to me there is absolutely no reason why the following doesnt work…

https://docs.unity3d.com/ScriptReference/Networking.NetworkManager.OnServerAddPlayer.html
i have basically the same code and still it doesnt work…

the error im given is that there is “no suitable method found etc” for OnServerAddPlayer
and please note that my script is inheriting NetworkManager

all help is appreciated

I had already done on script which inherited from NetworkManager and it seemed like that doesnt work, so for anyone else struggling with this, u cant have multiple custom networkmanager scripts