There could be multiple reasons why the DVD is not working like the DVD might have been corrupted, you might be having CD drive and trying to read DVD, or the DVD is not inserted correctly and so on.
You can install the trial version from the below link and use your serial number to activate:
But then it says that the serial number is invalid ????
Sorry for the delay.
Hmm. Check if the name and version of the software on the Activation window is same as the serial number that you have.
* Check the language and platform of both the media and the serial number.
* Check if you have logged on as an Admin.
Have you submitted your product code already to obtain your serial number? Please make sure you have submitted your proof of eligibility. You can find additional details at http://forums.adobe.com/message/4634728#4634728.