Could not load file or assembly 'System.Data.SQLite'

I've installed ELMAH 1.1 .Net 3.5 x64 in my ASP.NET project and now I'm getting this error (whenever I try to see any page):

Could not load file or assembly 'System.Data.SQLite, Version=1.0.61.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.BadImageFormatException: Could not load file or assembly 'System.Data.SQLite, Version=1.0.61.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139' or one of its dependencies. An attempt was made to load a program with an incorrect format.

More error details at the bottom.

My Active Solution platform is "Any CPU" and I'm running on a x64 Windows 7 on an x64, of course, processor. The reason why we are using this version of ELMAH is because 1.0 .Net 3.5 (x86, which is the only platform for which it's compiled) gave us this same error on our x64 Windows server.

I've tried compiling for x86 and x64 and I get the same error. I've tried removing the all compiler output (bin and obj). Finally I've made a reference to the SQLite dll directly, something that was not needed for the project to work on the server and I've got this compiler error:

Error 1 Warning as Error: Assembly generation -- Referenced assembly 'System.Data.SQLite.dll' targets a different processor MyProject

Any ideas what the problem might be?

More error details:

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[BadImageFormatException: Could not load file or assembly 'System.Data.SQLite, Version=1.0.61.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +43
System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +127 System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +142 System.Reflection.Assembly.Load(String assemblyString) +28
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +46

[ConfigurationErrorsException: Could not load file or assembly 'System.Data.SQLite, Version=1.0.61.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +613 System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +203 System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +105
System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +178
System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +54
System.Web.Compilation.ApplicationBuildProvider.GetGlobalAsaxBuildResult(Boolean isPrecompiledApp) +232
System.Web.Compilation.BuildManager.CompileGlobalAsax() +52 System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +337

[HttpException (0x80004005): Could not load file or assembly 'System.Data.SQLite, Version=1.0.61.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +58 System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +512 System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +729

[HttpException (0x80004005): Could not load file or assembly 'System.Data.SQLite, Version=1.0.61.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +8896783
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +85
System.Web.HttpRuntime.ProcessRequestInternal(HttpWorkerRequest wr) +259

System.Data.SQLite.dll is a mixed assembly, i.e. it contains both managed code and native code. Therefore a particular System.Data.SQLite.dll is either x86 or x64, but never both.

Update (courtesy J. Pablo Fernandez): Cassini, the development web server used by Visual Studio when you press F5 or click the green «play» button, is x86 only which means that even if your workstation is x64, you'll only be able to use the x86 version of System.Data.SQLite.dll.

An alternative is not to use Cassini but IIS7 which is properly x64.