Caller id not showing when screen is locked

[99ls1z]

I am having to slide the screen down enter the unlock sequence and then see how is calling. I have missed several calls by doing this. I can reboot the phone and it is back to normal. When phone locked pops up who's calling and can answer. Works fine for a few calls and then back to having to unlock phone first. The screen will just flash on and off. I have looked for a setting and can't find one. Any ideas?

 

[99ls1z]

anyone?