Problem Moving Rows in a UITableView

Question

I have a UITableView which has more rows than can be displayed on the screen at one time, i.e. it has scrolling. Here's the problem I'm having when moving rows around.

1. Move an onscreen row to an onscreen location. Works fine.
2. Scroll up to expose more rows at the bottom. Choose one of these rows to move up. When the row being moved reaches the top of the display, automatic scrolling takes place so the row being moved keeps on sliding up. Works great.
3. Choose an onscreen row to move down. When the row being moved reaches the bottom of the display automatic scrolling DOES NOT take place as in case (2) above. I am unable to slide the row down any further.

I have read the Apple docs but not sure why this is not working.