Control J not working

Hi, I'm having a strange issue since the last one or two Photoshop updates. Firstly, the keyboard shortcut Control-J is by default set to "Shape Layer Via Copy"... 

I've gone into "Keyboard shortcuts and Menus" to change Duplicate Layer (Group) to Control-J... but when I do it gives me the rror below, where it thinks I've pressed SHIFT-J.... I definitely have pressed Control-J... but it won't accept it.

Please help!