how to use TLRequestGetFullUser ? error {"USER_ID_INVALID"}

[elmagekmosaad]

var req = new TLRequestGetFullUser() { Id = new TLInputUser() { UserId = 1433024775 } };
var auser = Await client.SendRequestAsync(Of TLUserFull)(req)

it's return {"USER_ID_INVALID"}

also how to use TLRequestGetUsers