Watermark , will not work....

hello to all

, i have dolfin 6.1.2 my waterrmark does not work, in admin i can see the image uploaded, but when I go into fronted does not appear in any photos (watermark admin option is enabled....).

i tried to make the changes listed in this topic:

http://www.boonex.com/unity/forums/#topic/Watermark.htm

, but does not change anything ...

someone can help?