How to create Server function bp with delegate?

Hi. I wanted to know if its possible to create a function that runs on the server with specific inputs and a delegate. I made a UFUNCTION that runs on the client just perfectly, but when i add Server, WithValidation,Reliable to it, it immediately says that Delegates cannot be used AND that all the FString parameters are invalid conts. Why???

this is the ufunction declaration. I basically took the client call, added _Validate and _Implementation, with the new Server,Reliable,WithValidation parameters in the ufunction. Now i get errors. Is something like this not possible??? Why can i make functions in blueprints that can accomplish the same thing but not in CPP → BP???