WCF returning "The content type text/html; charset=utf-8 of the response message does not match"

The content type text/html; charset=UTF-8 of the response message does not match the content type of the binding (text/xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly. The first 1024 bytes of the response were..."

Any idea and Suggestions??