If your files meet the criteria to properly update a file, troubleshoot the issue by creating a log file to determine why the file is failing to update. To generate a log file, use the following command line: msiexec /p <full path to .MSP> /l*v <full path to log file>.  If you need assistance in understanding how to read the log file, then download the Windows Installer Verbose Setup Log Analyzer utility provided only by Microsoft. For more information on the utility, click on the following link: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/msi/setup/wilogutl_exe.asp.

If the version number of the file only changes within the fourth field, then you will need to update the file version number in the third field. If you cannot modify the file version number, or you do not meet the criteria to properly replace an existing file, then you will need to create a Wisescript that will delete the file before CostInitialize in the new .MSI.

Always run Upgradesync to compare your previous .MSI file against the new .MSI file to ensure that there are no errors in the way your patch was designed. To learn more about Upgradesync, review article# 26787 Using UpgradeSync to prepare for Patching and Upgrading.