I'm not able to unlock a profile with a charger.

Just attaching your charger is not enough. With the charger attached, you must go into the locked profile's detail page and press the little lock on the top right hand corner to unlock the profile. 

Occasionally, the profile cannot be unlocked even if the charger is connected. Try to reconnect the charger with the locked profile detail screen open and wait for a while, then try to unlock it again.

You cannot use the charger to unlock a profile which is locked for a set time. In this case, please wait for the timer to run out.