Can you elaborate please? To use a sign, the corresponding sign icon must be selected (glowing). Sometimes, when you enter a region from a "safe" zone, the sign doesn't get "selected" by default. You may have to select it again by clicking on the icon before you can use it. This was a problem in the original WItcher. I did not notice this problem in the EE, but I might have simply overlooked it, or corrected it out of habit. So remember, whenever you're trying to can a sign, make to sure the corresponding icon is glowing first.