ServiceStack: Deployment causes FileLoadException, can't load System.Runtime.Serialization

I've got a very simple ServiceStack service running, from a path /api/Translate/.... This works perfectly locally. I can view XML, JSON, etc.

However, when I deploy the project to the live environment, calling the service results in:

<TranslateResponse xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="">
- <ResponseStatus>
  <ErrorCode>FileLoadException</ErrorCode> 
  <Message>Could not load file or assembly 'System.Runtime.Serialization, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, Retargetable=Yes' or one of its dependencies. The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)</Message> 
  <StackTrace>at System.ModuleHandle.ResolveType(RuntimeModule module, Int32 typeToken, IntPtr* typeInstArgs, Int32 typeInstCount, IntPtr* methodInstArgs, Int32 methodInstCount, ObjectHandleOnStack type) at System.ModuleHandle.ResolveTypeHandleInternal(RuntimeModule module, Int32 typeToken, RuntimeTypeHandle[] typeInstantiationContext, RuntimeTypeHandle[] methodInstantiationContext) at System.Reflection.RuntimeModule.ResolveType(Int32 metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments) at System.Reflection.CustomAttribute.FilterCustomAttributeRecord(CustomAttributeRecord caRecord, MetadataImport scope, Assembly& lastAptcaOkAssembly, RuntimeModule decoratedModule, MetadataToken decoratedToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, Object[] attributes, IList derivedAttributes, RuntimeType& attributeType, IRuntimeMethodInfo& ctor, Boolean& ctorHasParameters, Boolean& isVarArg) at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeModule decoratedModule, Int32 decoratedMetadataToken, Int32 pcaCount, RuntimeType attributeFilterType, Boolean mustBeInheritable, IList derivedAttributes, Boolean isDecoratedTargetSecurityTransparent) at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeType type, RuntimeType caType, Boolean inherit) at System.RuntimeType.GetCustomAttributes(Type attributeType, Boolean inherit) at ServiceStack.WebHost.EndPoints.Utils.FilterAttributeCache.GetResponseFilterAttributes(Type responseDtoType) in C:\src\ServiceStack\src\ServiceStack\WebHost.EndPoints\Utils\FilterAttributeCache.cs:line 51 at ServiceStack.WebHost.Endpoints.EndpointHost.ApplyResponseFilters(IHttpRequest httpReq, IHttpResponse httpRes, Object responseDto) in C:\src\ServiceStack\src\ServiceStack\WebHost.EndPoints\EndpointHost.cs:line 205 at ServiceStack.WebHost.Endpoints.RestHandler.ProcessRequest(IHttpRequest httpReq, IHttpResponse httpRes, String operationName) in C:\src\ServiceStack\src\ServiceStack\WebHost.EndPoints\RestHandler.cs:line 64</StackTrace> 
  </ResponseStatus>
  </TranslateResponse>

The TranslateResponse being my otherwise healthy DTO. The ResponseStatus is not mine. I have checked .NET version targetting and have set System.Runtime.Serialisation to "Copy Local" and manually included the DLL in the /bin folder.

But it still does not work. Where am I going wrong?

Solved it.

It was the inclusion of a Project built using the Portable Class Library project. That thing seemed too good to be true. Have removed (which solves other issues, chiefly MVVM implementation) and all works.