You forgot to configure the source for the drop down

In General Tab

List Source

Select as Data page

Give the D_BooksList

Property for value : Phone , this is which value to select

Property for display text: Phone: Which value to display on screen

Hi,

There is an error in the source as pointed out above. As defined by property is used when a list is defined on a particular property, not as a pagelist.

Also there is an issue with the property configured on the drop down. 

The property configured is where the data will be stored after a value is selected from the dropdown. In this case you have chosen a generic page list. It doesnt have an index, so the system wouldnt understand under which page index to store the property. 

This configuration can be used only in conjugation with a grid where page context is known and you wont need to use the parent page.