WiX RemoveFolderEx 'Missing Folder Property' - wix

Question

I'm trying to use RemoveFolderEx to remove the Roaming/MyApp folder after uninstall, howver, after using the 'msiexec /i /l*v' command and checking the installer logs, I come across this:
MSI (s) (64:40) [10:30:45:254]: Invoking remote custom action. DLL:
C:\Windows\Installer\MSI860E.tmp, Entrypoint: WixRemoveFoldersEx MSI
(s) (64:74) [10:30:45:254]: Generating random cookie. MSI (s) (64:74)
[10:30:45:256]: Created Custom Action Server with PID 52380 (0xCC9C).
MSI (s) (64:8C) [10:30:45:657]: Running as a service. MSI (s) (64:8C)
[10:30:45:704]: Hello, I'm your 32bit Impersonated custom action
server. WixRemoveFoldersEx: Error 0x80070057: Missing folder
property: APPLICATIONFOLDER for row:
wrf4C77709F2CC40D572056B8DB1B2D0A3E CustomAction WixRemoveFoldersEx
returned actual error code 1603 but will be translated to success due
to continue marking Action ended 10:30:45: WixRemoveFoldersEx. Return
value 1.
I just cant seem to get it it to work. I followed this guide to implement it: http://www.hass.de/content/wix-how-use-removefolderex-your-xml-scripts
Here is my Wix code:
<Property Id="APPLICATIONFOLDER">
<RegistrySearch Key="Software\Wah\MyApp" Root="HKCU" Type="raw"
Id="REGSEARCH" Name="Path" />
</Property>
<Directory Id="TARGETDIR" Name="SourceDir">
<Directory Id="AppDataFolder">
<Directory Id="PrivateData" Name="MyApp">
<Component Id="RemovePrivateData" Guid="*">
<RegistryValue Root="HKCU" Key="Software\Wah\MyApp"
Name="Path" Type="string"
Value="[AppDataFolder]" KeyPath="yes"/>
<util:RemoveFolderEx On="uninstall"
Property="APPLICATIONFOLDER"/>
<RemoveFolder Id="AppDataFolder" On="uninstall"/>
</Component>
</Directory>
</Directory>
</Directory>
After looking at Regedit, the value does get set to the correct path.
Any help would be greatly appreciated as I've looked at practically every issue with RemoveFolderEx and it hasn't particularly helped.
EDIT: I've fixed this issue by adding a 'Secure="yes"' attribute to my APPLICATIONFOLDER property, like so:
<Property Id="APPLICATIONFOLDER" Secure="yes">
<RegistrySearch Key="Software\Wah\MyApp" Root="HKCU" Type="raw"
Id="REGSEARCH" Name="Path" />
</Property>