Thanks for your reply. I did have the Patient object defined correctly at first, but then changed it to see if it would make a difference.
private Patient Patient; instead of private Patient = new Patient();

I found out I had some issues with the names of my stored procedures. I couldn't get the MM.Net AAppTest to run correctly. I fixed that and tried to run from the main application again. I'm still getting the same error: "Object reference not set to an instance of an object." in this line of code:
this.Patient = (Patient)this.RegisterPrimaryBizObj(new Patient());


Is there supposed to be code in the HookConstructor() method in the partial.cs file for my business object (Patient in this case)? That method is empty and yet is called by the business object constructor. The MM.Net Dev Guide doesn't mention putting any code in there. But how is the object supposed to get the data from the data source if there are no data access calls?

Very confusing.

Thanks!

Lynn 8-)