The issue may be related to the root in some way even though it's not a root app. Are you running a custom software on the phone? It could possibly be a permissions error.
Some easy things to try would be to open your app manager in the settings and clear cache and data for the camera app.
You could try booting into recovery and running "fix permissions". Probably under advanced or similar.
You could try wiping cache/dalvik in recovery.
Without knowing everything you've done to the phone, it's impossible to pinpoint the exact issue.
You could also make a backup and return to stock. If the camera is working, then the issue is likely from something you did or changed.
You could also try a wipe and clean install of the rom. If you flashed your rom without wiping first, you may have some issues.