Why is the default value of REINSTALLMODE "omus" when you create a new Patch Configuration, but the recommended value when executing msiexec on the command line "vomus?"
The v is not required in a patch (.msp), only if you ship the update as a full .msi. And it has to be set outside the .msi file, on the command line. Setting REINSTALLMODE in property manager to include v would work.
Ok to explain clarify Stefan's comments a bit more....
Whenever you install an msi it caches the installation on your machine to be useful for uninstalls, reinstalls and repairs.
When you run a reinstall using just omus, it ignores the msi you provided it with and goes off to the cached version. specifying the v causes the msi to recache so it runs from your modified msi.
However an msp patch works slightly different. An msp is just a file containing changes and isn't a full msi. What it does is stream itself into the cached msi before running it. Therfore an msp cannot be cached itself but instead it updates the existing cache.
