Show The First Name In Datagridview For Some Date?

I have two linked tables in my database <the first is Patient include (number,first name and last name) and the other is Appointment include (number,date,time)I want to show the first name in datagridview for some date.I tried this code,but It won't work,I think something missing

Dim query = From pat In Me.ClinicDBDataSet.Patient, app In Me.ClinicDBDataSet.Appointment _
Where pat.Patient_No = app.Patient_No AndAlso app.App_Date > DateTimePicker1.Value AndAlso app.App_Date < DateTimePicker2.Value _
Select pat
PatientDataGridView.DataSource = query.AsDataView