AssImp Exception trying to build custom content


I’m trying to port my XNA 4.0 game to MonoGame, I grabbed the latest source and built it (in Visual Studio 2010) today. I’m just targeting Windows to start with.

We use custom content processors, so I created MonoGame projects for them, converted them to use “Any CPU” platform, and referenced MonoGame.Framework.Content.Pipeline.dll. They all seem to build fine and output the expected dlls.

In my Content.mgcb file, it correctly finds the processors and all seems well… Until the first fbx file it tries to build gives this error:

C:/dev/Miasma2Mono/Miasma2MonoContent/Content/Weapons/pistol.FBX : error : Importer ‘FbxImporter’ had unexpected failure!
Assimp.AssimpException: Error loading unmanaged library from path: Assimp64.dll, see inner exception for details.
Could not load file or assembly ‘MonoGame.Framework.Content.Pipeline.XmlSerializers’ or one of its dependencies. The system cannot find the file specified. —> System.IO.FileNotFoundException: Could not load file or assembly ‘MonoGame.Framework.Content.Pipeline.XmlSerializers’ or one of its dependencies. The system cannot find the file specified.
at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.LoadWithPartialNameInternal(AssemblyName an, Evidence securityEvidence, StackCrawlMark& stackMark)
— End of inner exception stack trace —
at Assimp.Unmanaged.AssimpLibraryWindowsImplementation.NativeLoadLibrary(String path)
at Assimp.Unmanaged.AssimpLibrary.LoadLibrary()
at Assimp.Unmanaged.AssimpLibrary.CreatePropertyStore()
at Assimp.AssimpContext.CreateConfigs()
at Assimp.AssimpContext.ImportFile(String file, PostProcessSteps postProcessFlags)
at Microsoft.Xna.Framework.Content.Pipeline.OpenAssetImporter.Import(String filename, ContentImporterContext context)
at Microsoft.Xna.Framework.Content.Pipeline.FbxImporter.Import(String filename, ContentImporterContext context)
at Microsoft.Xna.Framework.Content.Pipeline.ContentImporter`1.Microsoft.Xna.Framework.Content.Pipeline.IContentImporter.Import(String filename, ContentImporterContext context)
at MonoGame.Framework.Content.Pipeline.Builder.PipelineManager.ProcessContent(PipelineBuildEvent pipelineEvent)C:/dev/Miasma2Mono/Miasma2MonoContent/Content/Weapons/smach.FBX

Any ideas? Am I missing a reference or is it something with my data?