How To Auto-increment Primary Key When Adding A New Row Using Update Method?

Hi guys,
I followed the ASP.net official tutorial to create a DAL & Business Logic Layer (http://www.asp.net/learn/dataaccess/tutorial02cs.aspx). I have a table with a int ID field. I wish to write a function to add a new entry into this table but have the ID field auto-increment.
The ID field is set as the Identity Column and has a Identity Increment & Seed of "1". If I manually go to the table and insert a new record leaving the ID value null it automatically increments. But if I create a C# function to add a new entry I get an error saying that the ID field can't be Null. Is there any way to use the Update method as shown on line 14 below to add a new entry but with it automatically incrementing?
I did create a function called InsertDevice that simply inserts the other fields using a SQL INSERT and it auto-increments fine, just wondering if there is a way to do it using the DataTable and the Update method? Thanks for any help!!!

 
 1 public bool AddDevice(string make, string model)
2 {
3 //cannot have the same device entered twice!
4 if (Adapter.FillDeviceCountByMakeModel(make, model) == 1)
5 return false;
6
7 RepositoryDataSet.DevicesDataTable devices = new RepositoryDataSet.DevicesDataTable();
8 RepositoryDataSet.DevicesRow device = devices.NewDevicesRow();
9
10 device.make = make;
11 device.model = model;
12
13 devices.AddDevicesRow(device); << Error thrown Here!
14 int rows_affected = Adapter.Update(devices);
15
16 return rows_affected == 1;
17 }