Smart key application problem

[DIP9]

Hi, I hace brought new Xperia c3 dual 4 months ago from Ebay site.
I have installed Smart key application which is sponsored by Sony.
Smart key application able to custmise your headphones,headset,etc.. But in my smart key application there no option for "Call Default... Answer/End call"...
How can I enable it!??

[Qatrium]

@DIP9

I'm not sure but I think it depends on the connected headphones, maybe it doesn't support all the functions. You can try to refresh the app:

- Go to Settings -> Apps -> Smart Key -> Force stop, Clear data, Uninstall and restart your phone.
- Go to your Play Store and install Smart Key again.

[DIP9]

@Quester: I have original Sony Headphones,
I have tried other headphones also but it didn't work..
I have fillow yours Instructions but no effect.