Exception not being passed from remote client to local?

I'm having a problem with exceptions not being passed from the remote client to the local client.

The slice definition is:

exception ExceptionIceGeneral
{
string Description;
};

The C# server sits behind a Glacier2 firewall, and throws an exception thus:

throw new ExceptionIceGeneral("New Exception");

The C# client tries to intercept the exception:

catch (ExceptionIceGeneral e)
{
Console.Write("Exception is: {0}.\n", e.Description);
}

However, the code above does not intercept this exception: instead, the following exception handler is invoked:

catch (System.Exception ex)
{
Console.Error.WriteLine(ex);
}

However, this handler does not contain the "Description", so there is no way to tell what caused the error (the client prints "Ice.UnknownUserException", there is no correct "Description" string anywhere in "ex").