Assembly must be registered in isolation error

I'm trying to load a custom workflow activity onto a crm server. I loaded the project onto the server and have been using the CRM Plug-in Registration Tool. The server is CRM2011 and thus supports .NET 4.0 activities. However, when I press the "Register" button (After the assembly has successfully loaded onto the Tool) the following error occurs:

`Unhandled Exception: System.ServiceModel.FaultException'1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: Action failed for assembly 'ExecuteSQLJob, Version=1.0.0.0, Culture=neutral, PublicKeyToken=914788311ab3af7d': **Assembly must be registered in isolation**.
Detail: <OrganizationServiceFault xmlns="http://schemas.microsoft.com/xrm/2011/Contracts" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
  <ErrorCode>-2147220906</ErrorCode>
  <ErrorDetails xmlns:a="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
  <Message>Action failed for assembly 'ExecuteSQLJob, Version=1.0.0.0, Culture=neutral, PublicKeyToken=914788311ab3af7d': Assembly must be registered in isolation.</Message>
  <Timestamp>2012-06-21T19:50:30.5216535Z</Timestamp>
  <InnerFault>
    <ErrorCode>-2147220906</ErrorCode>
    <ErrorDetails xmlns:a="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
    <Message>Action failed for assembly 'ExecuteSQLJob, Version=1.0.0.0, Culture=neutral, PublicKeyToken=914788311ab3af7d': Assembly must be registered in isolation.</Message>
    <Timestamp>2012-06-21T19:50:30.5216535Z</Timestamp>
    <InnerFault i:nil="true" />
    <TraceText i:nil="true" />
  </InnerFault>
  <TraceText i:nil="true" />
</OrganizationServiceFault>`

`Server stack trace: 
   at System.ServiceModel.Channels.ServiceChannel.HandleReply(ProxyOperationRuntime operation, ProxyRpc&am