Cannot display Macbook Pro on external projector
Following ensuring the hardware is working (you did that)

The process:

Plug in initiates the hand shake (who are you)

Results in showing the details in About this Mac, or Sys Preferences Display.


check for correct display identified and what resolution was chosen.


Simultaneously Mac looked up in its database for what profile (plist) to use.

Simultaneously Mac selected a Display property (colors ect) profile.


can be seen (or modified) in the Color Sync utility application in your utility folder.


Check all above, and verify the process/sequence in your Console.