Weird Link when switch language

Hi,
I have a problem, when i switch language from default language to an other the link become incorrect.
eg. http://www.domainnaim.it is the link correct of default language, when i select an other language like english the link become http://www.domainname.it/en//en but it’s incorrect! It would be http://www.domainname.it/en

Can someone hepl me to fix the problem?

Thankyou.

http://wordpress.org/plugins/sitepress-multilingual-cms/