I'm trying to make use of WCF Test Client along with named pipes but I get the following error:

Error: Cannot obtain Metadata from net.pipe://localhost/MyService

Here's my web.config:

<system.serviceModel>
<services>
  <service name="MyNamespace.MyService" behaviorConfiguration="MEX">
    <endpoint address="net.pipe://localhost/MyService"
              binding="netNamedPipeBinding"
              contract="MyNamespace.MyService.IMyService"
    />
    <endpoint address="net.pipe://localhost/MEX"
              binding="mexNamedPipeBinding"
              contract="IMetadataExchange"
    />
  </service>
</services>
<client>
  <endpoint address="net.pipe://localhost/MyService"
            binding="netNamedPipeBinding"
            contract="MyNamespace.MyService.IMyService"
  />
</client>
<behaviors>
  <serviceBehaviors>
    <behavior name="MEX">
      <serviceMetadata />
    </behavior>
  </serviceBehaviors>
</behaviors>

What's wrong? I have tried both net.pipe://localhost/MyService and net.pipe://localhost/MEX.

Any help would be appreciated, thanks!