I have the same problem. I have just called my phone about 10 times and very carefully swiped. Two of the ten times it just would not answer and this was nothing to do with my swiping.
Happens to me also, it's the only thing I don't like about my Z10. I've lost a fair few calls due to them hanging up or going to voice mail.
The main issue is that to ensure you can pick up the call it's ended up as a two handed operation. One to hold it with the index finger of the other to swipe.
Much prefer to pick up one handed which might be why BlackBerry are rumoured to be changing the answer screen.
This is funny and probably why it was changed on 10.2.1 but I've never had that problem. I can assure you on the new leak you won't have a problem. The answer/decline swipe goes from left to right. It's pretty cool actually.
Instead of a light flick, do it a bit more forcefully. It might be a sensitivity issue to prevent accidental answering or accidental rejection of calls.
If you're still having problems, tap and hold, then drag down, or up.
Posted via CB10
^ THIS.
You definitely have to let the phone recognize that you have placed your finger on the bar and are either swiping up or down. I don't believe it's a software issue but more to this point that it's to prevent accidental answering or accidental rejection of calls.
It was a problem for many until 1791 OS...and they have fixed if in 1803 as far as I have noticed.
Also they have changed the Mechanism with 10.2.1 to swipe sideways
Posted via the awesome keyboard on Z10STL100-1/10.2.0.1791 using CB10 App
