As another clue, that indeed fixed this issue in my case.
I'm migrating some WCF services from a console application (that configures in code few WCF services) to an Azure WebRole to publish them in Azure. Every time I add a new service VS edits my web.config and adds this line:
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true">
Well, with all the advices and answers above I couldn't make it work until I removed all the attributes in the serviceHostingEnvironment element. As you can see I'm not a WCF rockstar but I made it to work with the first Service just by configuring it as:
<service name="FirstService" behaviorConfiguration="metadataBehavior">
<endpoint address=""
binding="wsHttpBinding"
bindingConfiguration="WSHttpBinding_WcfServicesBinding"
contract="IFirstService" />
</service>
but when I added the second Service it stoped working and I realized that those attributes where there again.
I hope it saves you time.