InstallShield package with CRRuntime_12_0.msm won't update previous version

I have an InstallShield 2009 package that includes the Crystal Reports 2008 runtime CRRuntime_12_0.msm. When I use this package to update a previously installed version of the application, it appears to go through the motions (although too fast) but does not update any of the files and does not display any errors. The previous version of the application was using the Crystal Reports 11.5 runtime.

If I remove the Crystal Reports 2008 runtime from the package, the rest of the update runs successfully.

Also, if I install on a machine that does not have a previous version of the app or if I first uninstall the previous version, the installation succeeds, so I know that my keycode is correct.

If anyone has any ideas as to why the CR 2008 runtime causes this failure, I would greatly appreciate hearing about it. Thanks in advance for any help.