Can not create alerts in moss2007 using API

Hello All,
I am trying to create alert's using SharePoint V3 API and for some
reason the properties I am setting does not affect in database. Here is
my code.

sPAlert6 = sPUser5.Alerts.Add();
sPAlert6.AlertType = SPAlertType.List;
sPAlert6.Title = "test alert";
sPAlert6.EventType = SPEventType.Delete;
sPAlert6.EventTypeBitmask = 2;
sPAlert6.AlertFrequency = SPAlertFrequency.Weekly;
sPAlert6.User = sPUser5;
sPAlert6.List = sPList;
sPAlert6.Update();

After executing this code following properties did not set what I am
trying to set in the database. However update method does not fail.

sPAlert6.EventType = SPEventType.Delete;
sPAlert6.EventTypeBitmask = 2;

After doing this if I see my alert in the browser following items were
set to default values.
1- Change Type
2- Send Alerts for These Changes

Can some body help me figure out why API is not saving the values what
I am setting, rather it is saving the default values.

Thanks
kashif