trying to configure pap chap

R1

interface Serial0/1/0

ip address 10.3.3.1 255.255.255.252

encapsulation ppp

ppp authentication pap chap

ppp pap sent-username R1 password 0 cisco

clock rate 2000000

R3

interface Serial0/1/0

ip address 10.3.3.2 255.255.255.252

encapsulation ppp

ppp authentication pap chap

ppp pap sent-username R3 password 0 cisco

clock rate 2000000

​

I am trying to search online and all of the tutorials are pap only and chap only. I've read that you can configure pap chap or chap pap together but the powerpoint doesn't include a sample configuration. I tried the configurations above and it doesn't work.