Duo Camera not working

I can't seem to get the duo camera feature working. Whenever I open the default camera app it tells me my duo camera is blocked, also if my hands are nowhere near it. The lens itself doesn't show any defects or obstructions. After a few seconds the message disappears again, but I don't seem to be using the duo camera since none of the related options (U-focus etc.) are available when I open the edit menu on the photos I've taken.:crying::(
PLZ HELP

I'm currently using an entirely stock phone (not rooted, locked, S-OFF), Hboot 3.19, CID HTC__11111, firmware version 3.31.512.2 , Android Kit Kat version 4.4.4

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