Why Set origin to 3d cursor won't work? I've got an object, and want to work on mirror modifyer with it, but I have first to change it's origin point. So I put my 3D cursor where i want to set the new origin point.
But when i do:
Object/Origin/Set Origin to 3D cursor
the origin point doesn't move. 

Is there a way to unlock this?

Edit: and I found that in the same scene I've got 2 objects, one I can move in object mode, and this particular one I cannot move it neither can I select it (in object mode)
Here's why :
In the Object context, the selectable property in the visibility window was unchecked.
Set it to selectable solved it all.

I was working on it only in edit mode, and in edit mode everything was selectable, here's why i didn't understood :/