WIX Custom Action Condition using Property Value not working - wix

Question

I am trying to run a custom action at the end of my Wix installer but only if certain conditions are met. The user runs through the installer and they will choose one of two modes that set the property 'ServiceType'. The two values for the property are "RegisterNew" and "LinkExisting". You can see by the log below that when the user selects "LinkExisting" in the UI that it changes the property but the custom action still runs.
MSI (c) (D4:44) [11:20:15:686]: PROPERTY CHANGE: Modifying ServiceType property. Its current value is 'RegisterNew'. Its new value: 'LinkExisting'.
Here is my custom action code:
<InstallExecuteSequence>
<Custom Action="RegisterServiceNameCustomAction" Before="InstallFinalize">
<![CDATA[(ServiceType="RegisterNew") AND (NOT Installed)]]>
</Custom>
</InstallExecuteSequence>
<Fragment>
<Binary Id="RegisterServiceCustomActionBinary" SourceFile="$(var.RegisterServiceCustomAction.TargetDir)$(var.RegisterServiceCustomAction.TargetName).CA.dll" />
<CustomAction Id="RegisterServiceNameCustomAction" BinaryKey="RegisterServiceCustomActionBinary" DllEntry="ShowRegisterService" Execute="deferred" Return="check" />
</Fragment>
Here are the different conditions I have tried:
(ServiceType="RegisterNew") AND (NOT Installed)
<![CDATA[(ServiceType="RegisterNew") AND (NOT Installed)]]>
ServiceType="RegisterNew" AND NOT Installed
Here is the code for my custom Dialog where they are selecting making their selection that will change "ServiceType":
<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
<Fragment>
<UI Id="SelectServiceDlg">
<Property Id="ServiceType" Value="RegisterNew" />
<Dialog Id="SelectServiceDlg" Width="370" Height="270" Title="[ProductName] [Setup]" NoMinimize="yes">
<Control Id="BannerBitmap" Type="Bitmap" X="0" Y="0" Width="370" Height="44" TabSkip="no" Text="[DialogBitmap]" />
<Control Id="BannerLine" Type="Line" X="0" Y="44" Width="370" Height="0" />
<Control Id="BottomLine" Type="Line" X="0" Y="234" Width="370" Height="0" />
<Control Id="Description" Type="Text" X="25" Y="23" Width="280" Height="40" Transparent="yes" NoPrefix="yes" Text="Determine whether you need to register a new service or link an existing service." />
<Control Id="Title" Type="Text" X="15" Y="6" Width="200" Height="15" Transparent="yes" NoPrefix="yes" Text="Service Type Selection" />
<Control Id="BothScopes" Type="RadioButtonGroup" X="20" Y="55" Width="330" Height="120" Property="ServiceType">
<RadioButtonGroup Property="ServiceType">
<RadioButton Value="RegisterNew" X="0" Y="0" Width="295" Height="16" Text="Register New Service" />
<RadioButton Value="LinkExisting" X="0" Y="60" Width="295" Height="16" Text="Link Existing Service" />
</RadioButtonGroup>
</Control>
<Control Id="RegisterNewServiceDescription" Type="Text" X="33" Y="70" Width="300" Height="36" NoPrefix="yes" Text="Select this option if you are going to register a new service.">
</Control>
<Control Id="LinkExistingDescription" Type="Text" X="33" Y="130" Width="300" Height="36" NoPrefix="yes" Text="Select this option if you are going to link an existing service to this service.">
</Control>
<Control Id="Back" Type="PushButton" X="180" Y="243" Width="56" Height="17" Text="!(loc.WixUIBack)" />
<Control Id="Next" Type="PushButton" X="236" Y="243" Width="56" Height="17" Default="yes" Text="!(loc.WixUINext)" />
<Control Id="Cancel" Type="PushButton" X="304" Y="243" Width="56" Height="17" Cancel="yes" Text="!(loc.WixUICancel)">
<Publish Event="SpawnDialog" Value="CancelDlg">1</Publish>
</Control>
</Dialog>
</UI>
</Fragment>
</Wix>
Here is an image of the UI:
So my question is why is it executing the custom action even though my condition is specifically checking that property?

Answer 1

After some reading of documentation and looking at all of the "properties" of the tag in WIX I decided to try and set a couple of other values and see what happened. I found that when defining the Property if you mark it as secure it then retains its value throughout the entire install process whereas if it is not secure it does not seem to do that. So now my property definition looks like this:
<Property Id="SERVICE_TYPE" Secure="yes" Value="RegisterNew" />
You'll notice that I had to change the name to call caps because when you mark a property as a secure property then you can not have any lowercase letters in the name.
Here is a snippet from the WIX documentation:
Secure -- YesNoType -- Denotes that the property can be passed to the server-side when doing a managed installation with elevated privileges. See the SecureCustomProperties Property for more information.
WIX Documentation For Property Element