I've searched for an answer but I still need help. I'm using Nova T 500 and mediaportal

I tried the suggestions here: http://www.geekzone.co.nz/forums.asp?forumid=84&topicid=20696 but none of them work. The thread is locked so I'm posting again.

The problem is that only some buttons of the buttons work with mediaportal such as the arrow keys, OK, mute, power and the star button. Other buttons such as GO, pictures, videos, music, TV launch mediacentre. How can I fix this? I've tried using the modified irremote.ini and trying to map keys on the mediaportal setup but I'm stuck now.