Ctrl + J doesn't work Currently I'm using the 'Cell Fracture Add-on' and want to remove the doubles. To do that I have to make all fractures into one single object so that I'm able to go into Edit Mode. Normally you only need to press Ctrl+J, but somehow nothing happens.

How can I fix this problem?
Make sure you are in Blender keyboard preset, not in Maya or 3DS Max keyboard shortcuts, then you will be able to do that by pressing Ctrl+J.