That worked perfect. However, I don't understand why. Is it because when the add to cart button is pressed, then the posted form element ID is created. Is that why I need both lines:
<input type="hidden" name="eCart1_1_ID_Add" value="101" >
<input type="hidden" name="ID" value="101" >
because it is querying for the value in the first line and the second line creates the ID = 101?
I am just trying to understand this so that I don't make the mistake again.
You and this forum are a great help to us less knowledgeable in php code.