a question about CustomListItem

I have built an XML view as follow:

<List

id="people_list"

class="sapUiResponsiveMargin"

headerText="Custom Content"

items="{people>/People}">

<items>

<CustomListItem>

<Button text="{people>ProductName}"/>

</CustomListItem>

<CustomListItem>

<Label text="{people>ProductName}"/>

</CustomListItem>

</items>

</List>

"people" is JSON model in walkthrough sample.

I want to show a list of customizing item, which has two levels, a button above and a label below.

But what I get is only Labels, with Buttons disappearing as the attached picture shows.

I am wondering what's wrong with my code.