WCF client fields are losing values

WCF client fields are losing values

I have a WCF service hosted on a console application the code is:
public interface ITestService
{
[OperationContract]
void SetField(string data);
[OperationContract]
string GetField();
}
public class TestService : ITestService
{
private string myData;
public string GetField()
{
retrun myData;
}
public void SetField(string data)
{
myData = data;
}
}
then I hosted it on a console application:
ServiceHost host = new ServiceHost(typeof(TestService));
host.Open();
Console.WriteLine("Test Service Host");
Console.WriteLine("Service Started!");
foreach (Uri address in host.BaseAddresses)
{
Console.WriteLine("Listening on " + address);
}
Console.WriteLine("Press any key to close the host...");
Console.ReadLine();
host.Close();
I started the console host then In an other console app I referenced the
service and used it:
TestService client = new TestService();
client.SetField("test");
Console.WriteLine( client.GetField() );
this print nothing means the field is still null
What is wrong with this service?