Mini-DisplayPort is NOT FOR USE WITH earlier Apple Macs that have Mini-DVI ... PLEASE CHECK YOUR PORT !!!!
Apple Mini-DisplayPort outputs on 2008 to 2009 MacBooks and iMacs are enabled for VIDEO ONLY.... Whilst new 2010 MacBooks and iMac (27 and 21.5) do support audio.
Mini DisplayPort (MALE) 1.1a input and HDMI (MALE) 1.3b output - Built in 1.8m HDMI cable means no need for an extra HDMI cable - Supports 1920 x 1200 - 1080p FULL HD - Deep Colour - x.v.Colour - HDTV Advanced Features eg. 200hz / 600hz etc.
Length : 1.8m - Colour : WHITE