Question to the PT2272-M4

Hi everyone,
I used the PT2272-M4 to build a reciever so i can eventually use an Arduino to control the door key of my House so i dont have to get up early Monday to let the Mailman in.

Now i set everthing to Adress 11111 and D so i can test it with my remote for the remote outlets.
It works quite well but it also sometimes works if i press button C or B.
My question is do i have to hook up any capacitor or something?

I got little switches hooked up for the adresse (pin 1-8 and 10-11) and a 1M ohm resistor between pin 15 and 16.
My input from an 433Mhz reciever goes straight into pin 14.
To finish it up i hooked an LED to pin 17 so i can see if it works.

Thanks a lot allready,