Topic: Adding Tags / practical Rails social Networking Sites (apress)

Hi,

I am trying to implement the "Adding Tags to the Photo Galery" chapter 10 from the practical Rails social Networking Sites (apress) book but it is not working for me: when I try adding tags nothing happens, the tags are not even saved in the database. I am not sure what I am doing wrong, I did follow the code in the book  (the chapter is available for download here:
http://www.apress.com/book/downloadfile/3577 }

If anyone has an idea where I should look in order to fix the problem, I would be extremelly grateful.