I tried many of the recommended answers (including the accepted one) and was getting a "Request Format is unrecognized" error when going to the ?wsdl url. What I found was that there was the following block in the parent folder of the webservice's web.config:

<webServices>
  <protocols>
    <remove name="Documentation" />
  </protocols>
</webServices>

That was removing the ability to access the WSDL information. Removing that "remove" tag and then following the accepted answer got it working.