Consumes a SOAP web service in a portable class library

I have a portable class library designed for the .NET framework 4.5, silverlight 4 and above, and Windows Phone 8. I want to use the SOAP service in this PCL using the service link.

    ServiceReference1.TadawulMarketServicePortTypeClient c = new ServiceReference1.TadawulMarketServicePortTypeClient(ServiceReference1.TadawulMarketServicePortTypeClient.EndpointConfiguration.TadawulMarketServiceSOAP11port_http, new EndpointAddress(""));
        c.getMarketSummaryCompleted+=c_getMarketSummaryCompleted;
        c.getMarketSummaryAsync();
    }

    private void c_getMarketSummaryCompleted(object sender, ServiceReference1.getMarketSummaryCompletedEventArgs e)
    {
      //  throw new NotImplementedException();
    }

when i use this code. In PCL, the service returns null, but when I use it in a Windows phone application, it returns data!

I wanted to know the reason for this and how to use this service correctly.