why doesn't the phone icon show up next to my name on facebook chat?

[heather motionless]

i only use facebook on my phone, but like most peoples', the little phone icon on the chat thing that says the last time you were on (like 5m, 2h, or whatever) shows up, but it never does that for me. i want it to. the little phone icon completely goes away within a minute, so it's just like i was never on at all & it's saying i'm not on my phone. can or how do i fix this?

[M!KEY]

i think it depends on what kind of phone you have

btw i can tell by your username that u listen to motionless in white