[wix-users] How to run executable custom action on uninstall

[Angus Comber]

I want to run a custom action to perform some system reverting actions
using custom action  CA_RemoveServerInstall like this:

    <Binary Id="RollbackServerInstallCA"
     SourceFile="installer_files/rollback-server.exe" />

    <CustomAction
        Id="CA_RemoveServerInstall"
        BinaryKey="RollbackServerInstallCA"
        Impersonate="no"
        ExeCommand="[INSTALLFOLDER] "Cuba Web Server""
        Execute="deferred"
        Return="ignore" />

    <InstallExecuteSequence>
      <Custom Action="CA_RollbackServerInstall" After="InstallFiles">Not
Installed</Custom>
      <Custom Action="CA_ServerConfig" After="CA_RollbackServerInstall">NOT
Installed</Custom>
      <Custom Action="CA_ServerInstall" After="CA_ServerConfig">NOT
Installed</Custom>
      <Custom Action="CA_StartServer" After="CA_ServerInstall">NOT
Installed</Custom>
      <Custom Action="CA_RemoveServerInstall"
After="InstallInitialize">Remove="ALL"</Custom>
    </InstallExecuteSequence>

But when I uninstall via Add/Remove programs I see a The Following
applications should be closed before continuing the install: Cuba Web
Server indicating that the custom action has not run yet.

And if I try to uninstall like this:

msiexec /x example11.msi /l*v uninstall.txt

then I get a Windows Installer dialog:
Another version of this product is already installed. Installation of this
version cannot continue. To configure or remove the existing version of
this product, use Add/Remove Programs on the Control Panel.

And the log shows:
MSI (s) (A0:F0) [12:18:13:215]: Note: 1: 1729

MSI (s) (A0:F0) [12:18:13:215]: Product: Example1 -- Configuration failed.



MSI (s) (A0:F0) [12:18:13:216]: Windows Installer reconfigured the product.
Product Name: Example1. Product Version: 1.0.0.0. Product Language: 1033.
Manufacturer: Itel Office Software Ltd. Reconfiguration success or error
status: 1638.



MSI (s) (A0:F0) [12:18:13:216]: MainEngineThread is returning 1638

MSI (s) (A0:A8) [12:18:13:217]: Calling SRSetRestorePoint API.
dwRestorePtType: 13, dwEventType: 103, llSequenceNumber: 811,
szDescription: "".

MSI (s) (A0:A8) [12:18:13:217]: The call to SRSetRestorePoint API
succeeded. Returned status: 0.

Another version of this product is already installed. Installation of this
version cannot continue. To configure or remove the existing version of
this product, use Add/Remove Programs on the Control Panel.

{6337C51E-6D21-4904-800C-CB7CEA4F33E1}

I need the custom action to run before any of the files are removed.  Is
the problem that the files are being removed before the custom action
runs?  Something else?