Mahout recommendation in implicit feedback situation

Good morning,
I've tried to create a recommender system using Mahout in an implicit
feedback situation. What I'm trying to do is explained exactlly in this
post on stack overflow:
http://stackoverflow.com/questions/23077735/mahout-recommendation-in-implicit-feedback-situation.
<http://stackoverflow.com/questions/23077735/mahout-recommendation-in-implicit-feedback-situation>
As you can see, I'm having some problem with it simply because I cannot
get the result that I expect (a value between 0 and 1) when I try to
predict a score for a specific item.

Someone here can help me, please?

Thank you in advance.

Alessandro Suglia