Problem description:
The problem may happen when UAC is enabled, it is usually because of the insufficient right to delete the registry key.
Solution:
1. Run installer in command prompt as administrator
2. Set custom action In-script execution to be Deferred Execution in System Context, this can work even if UAC is enabled and without using command line to install
Like Deferred Execution actions, these actions do not launch until the script generated by the Windows Installer service is run. However, actions of this type execute with no user impersonation.
Fix: When installing msi, custom action about deleting registy key does not work,布布扣,bubuko.com
Fix: When installing msi, custom action about deleting registy key does not work
原文：http://www.cnblogs.com/pengpenghappy/p/3897631.html