Unable to publish metadata

Hi All,
I have never faced something like this before, is it .Net 4.0? or Me?
Here is my config file
<system.serviceModel>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" aspNetCompatibilityEnabled="true" />
    <services>
      <service name="LookUpService" behaviorConfiguration="LUSBehavior">
        <host>< ...