How can I run .msi installer with administrator rights?

See: Special Installation Instructions for the ActiveGanttVBA & ActiveGanttCSA Gantt Scheduler Components

To circumvent this error, extract and double click on the:

Install_As_Administrator.reg

File that is included in the Install_As_Administrator.zip file distribution that can be downloaded from the top link on this page. This file will modify the Windows Registry to include the following information:

[HKEY_CLASSES_ROOT\Msi.Package\shell\runas]
@="Install &As Administrator..."

[HKEY_CLASSES_ROOT\Msi.Package\shell\runas\command]
@="msiexec /i \"%1\""

Once the Windows Registry has been modified using the Install_As_Administrator.Reg patch you can right click on any Windows Installer (*. msi) file and select the option Install As Administrator and the .msi file will run using elevated permissions (Administrator Permissions).

Hitting Shift while clicking on the MSI and then running as a different user and putting in my credentials allowed me to run my MSI. I did this even though I was logged in with those credentials.