I have a client-activated object that is failing with a
RemotingException. The exception's message is "The method '.ctor' was
not found on the interface/type 'My.Type, MyTypeLibrary,
Version=1.0.2371.15203, Culture=neutral, PublicKeyToken=null'.".

The client code is hosted in Internet Explorer; the server code is
hosted in IIS, using the binary channel over HTTP.

The client is using the following config values:
 <system.runtime.remoting>
   <application>
     <client url="http://localhost/MyVirtualDir/">
       <activated type="My.Type, MyTypeLibrary"/>
     </client>
     <channels>
       <channel ref="http">
         <clientProviders>
           <formatter ref="binary" />
         </clientProviders>
       </channel>
     </channels>
   </application>
 </system.runtime.remoting>

The server web.config includes:
    <system.runtime.remoting>
        <application>
            <service>
                <activated type="My.Type, MyTypeLibrary"/>
            </service>
            <channels>
                <channel ref="http">
                    <serverProviders>
                        <formatter ref="binary"/>
                    </serverProviders>
                </channel>
            </channels>
        </application>
    </system.runtime.remoting>

The MyTypeLibrary does exist in the web application's bin directory.

One other oddity is that the IE-hosted control is being served from a
different virtual directory. The file structure looks like this:
MyVirtualDir (virtual dir)
-> \bin
-> \bin\MyTypeLibrary.dll
-> \DownloadBin (virtual dir, from elsewhere in the filesystem)
-> \DownloadBin\MyControl.dll

The full stack trace (at the point where it leaves my code) is:

Server stack trace:
  at
System.Runtime.Remoting.Activation.LocalActivator.GetMethodBase(IConstructionCallMessage
msg)
  at
System.Runtime.Remoting.Activation.LocalActivator.Activate(IConstructionCallMessage
ctorMsg)
  at
System.Runtime.Remoting.Activation.ActivationListener.Activate(IConstructionCallMessage
ctorMsg)
  at
System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr
md, Object[] args, Object server, Int32 methodPtr, Boolean
fExecuteInContext, Object[]& outArgs)
  at
System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle
md, Object[] args, Object server, Int32 methodPtr, Boolean
fExecuteInContext, Object[]& outArgs)
  at
System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage
msg, Int32 methodPtr, Boolean fExecuteInContext)

Exception rethrown at [0]:
  at
System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage
reqMsg, IMessage retMsg)
  at
System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData&
msgData, Int32 type)
  at
System.Runtime.Remoting.Activation.IActivator.Activate(IConstructionCallMessage
msg)
  at
System.Runtime.Remoting.Activation.LocalActivator.DoRemoteActivation(IConstructionCallMessage
ctorMsg)
  at
System.Runtime.Remoting.Activation.LocalActivator.Activate(IConstructionCallMessage
ctorMsg)
  at
System.Runtime.Remoting.Activation.AppDomainLevelActivator.Activate(IConstructionCallMessage
ctorMsg)
  at
System.Runtime.Remoting.Messaging.ClientContextTerminatorSink.SyncProcessMessage(IMessage
reqMsg)
  at
System.Runtime.Remoting.Activation.ActivationServices.Activate(RemotingProxy
remProxy, IConstructionCallMessage ctorMsg)
  at System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(IMessage
reqMsg)
  at
System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData&
msgData, Int32 type)
  at My.Type..ctor(Boolean param)

There is no InnerException.

How should I go about debugging this? The site has FullTrust in the CAS
policy (I've already verified that). Why is it not finding the
constructor?