I was able to enter the Receiving Address, where I sent 2 payments, the 2nd payment was confirmed by the Blockchain, only in Elecrtum the booking is missing. Is that normal?
No, that's not normal. If you've sent funds to an adress belonging to an Electrum wallet, it should show an incoming amount from the moment the transaction got broadcasted.
As ranochigo stated:
Is your Electrum connected to a node/updating?
Is that dot which states "Network" green or red?
RED= Disconnected, probably something wrong with your firewall/wifi, which means the balance/incoming transaction never have been updated.
GREEN= Connected, which means you probably send the coins to the wrong adress/got phished into sending the coins to someone else's adress.