Web service result set data binding to a datagrid.

Hi,

I'm calling a third party web service like:

Exams.ExamBookingService.ExamBookingServiceSoapClient target = new Exams.ExamBookingService.ExamBookingServiceSoapClient();
                GetExamsServiceResponse esr;
               
Where response object is:

[DataContract(Namespace ="http://schemas.homelearningcollege.com/")]
    public class GetExamsServiceResponse    : ServiceResponse
    {

         [DataMember]//
        public List<ExamsDisplay> ExamsDisplay { get; set; }
       
    }

This is what I'm doing in my web form:

                esr = target.GetActiveExams("O6UJ9A001SUJ", "241222576");
                GridView1.DataSource = esr;
                GridView1.DataBind();

And I'm getting the following error:

datasource is an invalid data type. it must be either an IListSource, IEnumarable or IDataSource.

Can anybody advice me please!

Thanks in advance!