Adobe Acrobat 9 pro serial number issues

[Antonio29291212srp1]

I purchase the ADOBE ACROBAT 9 PRO, and I still have the Serial number, but when I have try to reinstall this in my laptop I get a message that the serial number is incorret, please instruct me what I have to do, I do not want purchase any upgrade.

[DeanUtian]

Take care not to duplicate your question in multiple posts. I added an answer in your other post at:
https://community.adobe.com/t5/acrobat-discussions/adobe-acrobat-xi-pro-installation-serial-number-i...