Installer Package always corrupt

Hi, regardless of aircraft, installer packages never work for me. I get the following error message:
The application could not be installed because the AIR file is damaged. Try obtaining a new AIR file from the application author.
I'm using WinRar to extract. Help would be greatly appreciated!
Clipper
The application could not be installed because the AIR file is damaged. Try obtaining a new AIR file from the application author.
I'm using WinRar to extract. Help would be greatly appreciated!
Clipper