Now just another thought have you set category permissions on what groups can vote under admin edit categories.
The code is very specific.
Code:
Content visible to verified customers only.
Here is what has to happen for a vote link to be shown. The category in question must be set to voting not rating. The image can not be your own and you can not have already rated it and you have to be logged in and the category permissions must be set on which groups can vote on images in the category.