Sleep/lock not working?

[3Flames]

Wirelessly posted (Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; en-gb) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5)

Whenever I hit the lock button with an app open, my screen goes dark, like it should do - the the lock screen flashes up, and I have to lock it again. This lockscreen is different, as the slider is lower on the screen. When locking it FROM the lockscreen though, it works perfectly. It's not due to another theme/tweak. What can I do?

 

[Tech Elementz]

I have experienced this before with an app, and think it's normal to happen, mainly because you do not properly close out of the app before you lock your screen.

 

[3Flames]

What? But I never close apps before locking - so even when I'm listening to music, I have to close the app, and if I want to change the song/album, I have to unlock, open the music app, close it, and then lock again? That doesn't seem right... Also, it sometimes happens when I'm on the springboard - i.e. don't have any app open at all.

EDIT: Disabling SleepFX fixes it, but I don't know why - it worked fine before...