For security reasons DTD is prohibited in this XML document.

HI ,

I am developing an app which has PCL,where I am calling a WCF service.
I have followed step wise step from

https://developer.xamarin.com/guides/cross-platform/application_fundamentals/web_services/walkthrough_working_with_WCF/

private async void button_Clicked(object sender, EventArgs e)
{

                objService.InsertAsync(c.name, c.OP);

    }

but I am not able to insert ,getting following error-

For security reasons DTD is prohibited in this XML document. To enable DTD processing set the DtdProcessing property
on XmlReaderSettings to Parse and pass the settings into XmlReader.Create method.

Could you please help urgently.