Question [Q] HDMI not working

Hello. I've seen that when i connect my tablet to my TV, it doesn't shows nothing, but on the Tf300T appears in the notification bar the HDMI notification, co i can access to the hdmi settings. I don't know if this is a build related problem, now i'm on 10.6.1.27.5 and i haven't used hdmi for a long time. Some help? Thanks and sorry for my bad english