It seems that there is a bug with the zip file you posted on this lesson. To reproduce this bug, please follow the following steps exactly.

Download the zip file from Developer Lesson 15.

Unzip Customer-Template-AFTER-D15-L03.zip and open the database.

1. Open CustomerChangeActiveF form

2. Click "Rost Richard" on the left list box to select it

3. Click >> Button

4. Select all items from the right list box by a combination of mouse clicks and the shift key

5. Click << button

6. Click SELECT ALL button

7. Click >> button

8. Select all items from the right list box by a combination of mouse clicks and the shift key

9. Click << button

10. Click "Jones Sue" to select it (Fig. 1)

11.Click >> button

12. You will notice that 4 people have been moved, eventhough only one is selected.

It seems that certain combination of mouse clicks would cause this bug and I notice similar bugs with my own code.

What is causing this bug? I have been pulling my hair out for 3 days and I couldn't figure it out.