The document at the url was not recognized as a known document type.

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WCF

service

Scenario Description:
1) Created a WCF project and publish it in IIS as a service. Its WSDL can be viewed by clicking the service's Manage Web Site > Browse at the site: http://localhost:48677/Service1.svc/GetDataTable
2) Created an application project, and tried add the WCF service as a Service Reference. I received he error:
The document at the url http://localhost:48677/Service1.svc/GetDataTable was not recognized as a known document type.

The error message from each known type may help you fix the problem:
- Report from 'XML Schema' is 'The root element of a W3C XML Schema should be <schema> and its namespace should be 'http://www.w3.org/2001/XMLSchema'.'.
- Report from 'DISCO Document' is 'Discovery document at the URL http://localhost:48677/Service1.svc/GetDataTable could not be found.'.
  - The document format is not recognized.
- Report from 'WSDL Document' is 'There is an error in XML document (1, 2).'.
  - <GetDataTableResponse xmlns='http://tempuri.org/'> was not expected.
Metadata contains a reference that cannot be resolved: 'http://localhost:48677/Service1.svc/GetDataTable'.
The remote server returned an unexpected response: (405) Method Not Allowed.
The remote server returned an error: (405) Method Not Allowed.
If the service is defined in the current solution, try building the solution and adding the service reference again.

Question: How can I debug this?
Thanks.