NHibernate.XmlSerializers - Does not it exist?

  

Could not load file or assembly   'NHibernate.XmlSerializers, Version = 4.0.0.4000, Culture = neutral,   PublicKeyToken = aa95f207798dfdb4 'or one of its dependencies. O   system can not find the file specified.

My application started requesting a DLL that does not exist before it was minhaapp.dll.XmlSerializers so I added that code to the project and the error changed from "address" and went to the NHibernate DLL

<Target Name="AfterBuild" DependsOnTargets="AssignTargetPaths;Compile;ResolveKeySource" Inputs="$(MSBuildAllProjects);@(IntermediateAssembly)" Outputs="$(OutputPath)$(_SGenDllName)">
    <!-- Delete the file because I can't figure out how to force the SGen task. -->
    <Delete
      Files="$(TargetDir)$(TargetName).XmlSerializers.dll"
      ContinueOnError="true" />
    <SGen
      BuildAssemblyName="$(TargetFileName)"
      BuildAssemblyPath="$(OutputPath)"
      References="@(ReferencePath)"
      ShouldGenerateSerializer="true"
      UseProxyTypes="false"
      KeyContainer="$(KeyContainerName)"
      KeyFile="$(KeyOriginatorFile)"
      DelaySign="$(DelaySign)"
      ToolPath="$(TargetFrameworkSDKToolsDirectory)"
      Platform="$(Platform)">
      <Output
       TaskParameter="SerializationAssembly"
       ItemName="SerializationAssembly" />
    </SGen>
  </Target>

Does anyone have any suggestions?