mac book pro won't go into clamshell mode

[brandontod97]

i have a macbook pro 13 inch mid 2009 and when i plug in my display (a vizio tv) using the mini dvi or what ever port apple uses for displays my mac doesn't go into clamshell mode when i close it and i don't know what pleases help i am running mac lion 10.7

 

[ergdegdeg]

Do you also have an external keyboard/mouse connected? You'll need to use those to wake up the computer once you close the lid.

 

[alFR]

Do you also have an external keyboard/mouse connected? You'll need to use those to wake up the computer once you close the lid.

Not on Lion - the laptop will stay awake when the lid closes, the internal screen will go off though. OP, what exactly do you mean by it won't go into clamshell mode? Does the laptop screen stay on? No display on the external screen?

 

[Taz Mangus]

Make sure that the power source is connected to the MacBook Pro. I don't think it will work correctly until the power source is connected.

 

[harcosparky]

Make sure that the power source is connected to the MacBook Pro. I don't think it will work correctly until the power source is connected.

BINGO!

I had to connect the external power to get it working on my 2011 MBP.