Camera [Q] Unable to connect to camera

hi guys i have been using a customer CM11 rom for my mega for a few months already.

however recently, after using any ROM for a while, whenever i go to the camera app, the error message always pops out "unable to connect to camera". I need to reboot my phone before being able to access the camera again, but after a few days the same thing happens.

Any idea why this happens? almost every CM11 rom i tried have the same issue!