We really need more information in order to try and help.
Please confirm you are trying to install FTM 2012, if not which version.
Do you have a previous version of FTM installed?
What is your Operating system? (XP, WIN7, WIN8)
Are you on a network?
Are you installing from CD, from network or download?
At what step in the installation process is the error message showing up?
you can always call 1-800-262-3787 -- Agents are available 7 days a week, 10 am to 10 pm EST or other numbers at http://www.familytreemaker.com/Support/Contact