concurrency error in tutorial

Hello,

I'm following a tutorial on this link :

http://www.homeandlearn.co.uk/csharp/csharp_s12p11.html

I find the tutorial very good and easy, but at the stage where we try to delete a record we always get a concurrency error.

The person who created the tutorial knows this too, but doesn't seem to give a correct solution.

What happens ?

- We add a new record
- When we try to delete the record immediatly, we get the error
- But when we exit the application and re-open it we can delete the record without a problem.


Maybe the person we gives the tutorial doesn't use the correct code to delete a record?