WCF Error . Unable to return in Json format

Hello,

 

When Im trying to run the service, Im getting the below error message

 

Im using this url which is hosted on my IIS

 

http://localhost/K2RestAPI/RESTService.svc/GetWorkList?/processName=&resultType=Assigned  

The XML page cannot be displayed

Cannot view XML input using style sheet. Please correct the error and then click the Refresh button, or try again later.

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The download of the specified resource has failed. Error processing resource 'http://localhost/K2RestAPI/RESTService.svc/Ge...