prop.exe elevated execution in Wix - wix

Question

This question seems to have been answered ad nauseam on this web site but I cannot get Wix to run an exe with Administrator rights (Windows 8.1 64-bit).
The installer I develop copies the prop.exe utility (http://prop.codeplex.com/) to a folder under Program Files (appfolder) as well as a file (my_file.propdesc) which needs to be registered/unregistered by prop.exe like:
prop schema register my_file.propdesc (at the end of installation)
prop schema unregister my_file (at the beginning of uninstallation)
These two command lines need to be run with Administrator privileges. Because these should also be run without a command prompt, I've used CAQuietExec with another CustomAction preparing the argument for CAQuietExec (prop.exe is 32-bit so it's CAQuietExec instead of CAQuietExec64 if I am not mistaken).
<CustomAction Id='PropReg_Prep' Property='PropReg' Value='"[appfolder]prop.exe" schema register "[appfolder]my_file.propdesc"' Execute='immediate' />
<CustomAction Id='PropUnReg_Prep' Property='PropUnReg' Value='"[appfolder]prop.exe" schema unregister "[appfolder]my_file.propdesc"' Execute='immediate' />
<CustomAction Id="PropReg" BinaryKey="WixCA" DllEntry="CAQuietExec" Execute="deferred" Return="ignore" Impersonate="no" />
<CustomAction Id="PropUnReg" BinaryKey="WixCA" DllEntry="CAQuietExec" Execute="deferred" Return="ignore" Impersonate="no" />
The custom actions are executed as per:
<InstallExecuteSequence>
<Custom Action="PropReg_Prep" After="CostFinalize" >NOT Installed</Custom>
<Custom Action="PropUnReg_Prep" After="CostFinalize" >Installed</Custom>
<Custom Action="PropUnReg" After="InstallInitialize" >Installed</Custom>
<Custom Action="PropReg" After="InstallFiles" >NOT Installed</Custom>
</InstallExecuteSequence>
I cannot get prop to register/unregister my_file.propdesc. Could someone help?

Answer 1

You are scheduling the actions as Execute='immediate' this runs as the user that executes the installer.
Switch to using Execute='deferred' this will run as the system account. Assuming that the prop.exe doesn't require a full profile to run this should work.

Answer 2

When you're not impersonating you're running with the system account, that's got admin privileges but if you are expecting it to be a user account then there might be issues.
The thing that looks weird to me is that [appfolder]prop.exe for a number of reasons. It doesn't look like a proper application folder, so make sure it's correct. It also needs to be in uppercase, making it a public property, and you should mark it Secure="yes" in the property element. The issue is that it may not get properly transferred from your immediate CA into the execute sequence where it's used.
p.s. Do the install creating a verbose log so you can see how those directory vales are actually being resolved at run time.