Wcf service (dt method) not able to acess in client app

Question

hi friends
 i have developed a service in wcf say datatable method

i am not able to access in client app

public DataTable Grid(WcfThreetierData obj1)

    {

        con.Open();

        cmd = new SqlCommand("PROC_WCF_GRID", con);

        cmd.CommandType = CommandType.StoredProcedure;

        da = new SqlDataAdapter(cmd);

        da.Fill(dt);

        con.Close();

        return dt;

    }

rest all the methods are able access

The error is 
"An error occurred while receiving the HTTP response to http://gunnala-pc/wcfthreetier/wcfthreetier.svc. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down)."

please suggest