I have a WIX installer that executes Custom Actions over the course of install. When I run the WIX installer, and it encounters its first Custom Action, the installer fails out, and I receive an error in the MSI log as follows:

Action start 12:03:53: LoadBCAConfigDefaults. SFXCA: Extracting custom action to temporary directory: C:\DOCUME~1\ELOY06~1\LOCALS~1\Temp\MSI10C.tmp-\ SFXCA: Binding to CLR version v2.0.50727 Calling custom action WIXCustomActions!WIXCustomActions.CustomActions.LoadBCAConfigDefaults Error: could not load custom action class WIXCustomActions.CustomActions from assembly: WIXCustomActions System.BadImageFormatException: Could not load file or assembly 'WIXCustomActions' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded. File name: 'WIXCustomActions' at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.AppDomain.Load(String assemblyString) at Microsoft.Deployment.WindowsInstaller.CustomActionProxy.GetCustomActionMethod(Session session, String assemblyName, String className, String methodName)

... the specific problem from above is "System.BadImageFormatException: Could not load file or assembly 'WIXCustomActions' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded."

The wordage of that error seems to indicate something like an incorrectly referenced .NET framework or something (I'm targeting 3.5 in both my custom actions and its dependencies), but I can't figure out where to make a change to address this problem. Any ideas?

.... Not sure if this will help but it's the CustomActions package batch file I run to create the .dll package containing the custom action functions:

===============

call "C:\Program Files\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"

@echo on

cd "C:\development\trunk\PortalsDev\csharp\production\Installers\WIX\customactions\PAServicesWIXCustomActions"

csc /target:library /r:"C:\program files\windows installer xml v3.6\sdk\microsoft.deployment.windowsinstaller.dll" /r:"C:\development\trunk\PortalsDev\csharp\production\Installers\WIX\customactions\PAServicesWIXCustomActions\bin\Debug\eLoyalty.PortalLib.dll" /out:"C:\development\trunk\PortalsDev\csharp\production\Installers\WIX\customactions\PAServicesWIXCustomActions\bin\Debug\WIXCustomActions.dll" CustomActions.cs

cd "C:\Program Files\Windows Installer XML v3.6\SDK"

makesfxca "C:\development\trunk\PortalsDev\csharp\production\Installers\WIX\customactions\PAServicesWIXCustomActions\bin\Debug\BatchCustomerAnalysisWIXCustomActionsPackage.dll" "c:\program files\windows installer xml v3.6\sdk\x86\sfxca.dll" "C:\development\trunk\PortalsDev\csharp\production\Installers\WIX\customactions\PAServicesWIXCustomActions\bin\Debug\WIXCustomActions.dll" customaction.config Microsoft.Deployment.WindowsInstaller.dll