Wix post-install and pre-uninstall executables - wix

Question

I'm using wix to create an installer for my application in Visual Studio.
I need a post-install executable run after install (which I've got working) and a pre-uninstall executable run before uninstallation.
All of these executables require elevated rights to run (my application, the post-install, and pre-uninstall).
I've scoured the web and stack overflow and found many posts related to this, but none of the solutions seem to work. Either the executables simply don't run, or, on uninstall I get error
There is a problem with this Windows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor.
Here is my Directory layout
<Fragment>
<Directory Id="TARGETDIR" Name="SourceDir">
<Directory Id="ProgramFilesFolder">
<Directory Id="ROOTDIRECTORY" Name="MyCompany" >
<Directory Id="FOLDERONE" Name="FolderOne" />
<Directory Id="UTILITYFOLDER" Name="Utility" />
</Directory>
</Directory>
</Directory>
</Fragment>
And a snippet of my File layout
<Fragment>
<DirectoryRef Id="UTILITYINSTALLFOLDER">
<Component Id="cmpPreInstallId" Guid="{56DC3D0A-E887-4A94-95B3-72825310DC5D}">
<File Id="filPreInstallId" KeyPath="yes" Source="path_to\PreUninstall.exe" />
</Component>
<Component Id="cmpPosUninstallId" Guid="{DE1DE45E-4D7C-4884-BA3E-EC078E265B7C}">
<File Id="filPostUninstallId" KeyPath="yes" Source="path_to\PostInstall.exe" />
</Component>
<!-- obviously there are other files/components -->
</DirectoryRef>
</Fragment>
<Fragment>
<ComponentGroup Id="UtilityPublishedComponents">
<ComponentRef Id="cmpPreInstallId" />
<ComponentRef Id="cmpPosUninstallId" />
</ComponentGroup>
</Fragment>
And in my Product.wxs
<Product ...>
<!-- The only way I found that actually worked to run the post install was -->
<UI>
<UIRef Id="WixUI_Minimal" />
<Publish Dialog="ExitDialog"
Control="Finish"
Event="DoAction"
Value="PostInstallExe">WIXUI_EXITDIALOGOPTIONALCHECKBOX = 1 and NOT Installed</Publish>
</UI>
<Property Id="WIXUI_EXITDIALOGOPTIONALCHECKBOXTEXT" Value="Perform post-install operations." />
<Property Id="WIXUI_EXITDIALOGOPTIONALCHECKBOX" Value="1"/>
<Property Id="WixShellExecTarget" Value="[#filPostUninstallId]" />
<CustomAction Id="PostInstallExe"
BinaryKey="WixCA"
DllEntry="WixShellExec"
Impersonate="yes" />
<!-- this does not work to run the pre-uninstall -->
<CustomAction Id="EXECUTE_BEFORE_UNINSTALL"
Return="check"
Impersonate="yes"
Execute="immediate"
Directory="UTILITYINSTALLFOLDER"
ExeCommand="PreUninstall.exe" />
<InstallExecuteSequence>
<Custom Action="EXECUTE_BEFORE_UNINSTALL" Before="RemoveFiles">Installed AND NOT REINSTALL</Custom>
</InstallExecuteSequence>
<!-- other stuff plus the feature -->
</Product>
Anyone with experience see where this might be going wrong?
I've tried many variations of the CustomAction return, impersonate, execute, etc

Answer 1

Finally got it to work, so hopefully this helps someone.
Not sure what the issue was ... but here!
<!-- Setup post install operations -->
<CustomAction Id="PostInstall"
FileKey="key_to_post_install_exe"
ExeCommand=""
Execute="deferred"
Return="check"
Impersonate="no" />
<!-- Setup pre uninstall operations -->
<CustomAction Id="PreUninstall"
FileKey="key_to_pre_uninstall_exe"
ExeCommand=""
Execute="deferred"
Return="ignore"
Impersonate="no" />
<!-- Add pre and post install operations to the installer -->
<InstallExecuteSequence>
<Custom Action="PostInstall" Before="InstallFinalize">NOT Installed</Custom>
<Custom Action="PreUninstall" After="InstallInitialize">Installed</Custom>
</InstallExecuteSequence>