Adjustment Layers Just Not Working

Before asking this I tried to search for an answer like EVERYWHERE, but it looks like I'm the only poor soul having this problem: after applying s_shake to an adjustment layer, placing it above the decided clip and starting the preview literally nothing happens. No effects, nothing. I made sure it was visible, I even changed the opacity, but nothing. This is driving me crazy because when I apply it to the chosen clip it works like a charm, still when I apply it to the a. layer and double click on it just a white screen shows up. Hell, it doesn't even shake! Can somebody please tell me what I could be doing wrong? Thanks alot