Android :: Implement An Activity That Uses ExpandableListView

Im trying to implement an activity that uses ExpandableListView and I have gotten so far but now I have found some strange behavior.

My activity is meant to record food intake as specified by the user. they have a choice of menus (breakfast, lunch and dinner - the outer group) which expand to show their contents.
when a user clicks on an inner menu item a dialog appears asking them for the qty. once they enter a qty and dismiss the dialog the text on the menu item changes to reflect the quantity of that item that has been consumed

The above image shows the list in a closed state.

Below is the list after I have opened the lunch menu and clicked on 'Potato Chips' and indicating a Quantity of 1. As you can see the 'Potato' itemtext has now been changed to reflect the Qty of 1.

The strange part happens now. if I click on 'Lunch' and close the list and then click on it again re-opening it, the 'Qty X 1' text has jumped to another item (Milk)

Each time I open and close the list it jumps back and forth between the two items. Also if I open up other items, such as breakfast, I find that they too have now gotten items with 'Qty X 1' even though I havent clicked them.

The bits of code that are relevant are as such:

The XML for a child element:

CODE:................

The code thats triggered on clicking a child element:

CODE:..................

The above code opens a dialog, accepts a value for quantity, appends the list element to reflect this, also saves to database and sets a textview with the selected item and quantity.