usually, if you place a sign down, it will open a gui which lets you input the text, if you put a sign on top or on the side of a fence or nether-fence, it does not open the gui, so it will place as an empty sign.
MC-19685
When Signs are put on any fence, it does not open the sign gui
Resolved
Duplicate
0
nick
(Unassigned)
Unconfirmed
Minecraft 1.6.1
Retrieved
Duplicate of MC-19082, please use the search function to see if your bug has already been submitted. Currently over 57% of tickets are being closed as duplicate.