Screen reader does not read the listbox options in firefox

I have simple autosuggest that displays the suggestions on the basis of user input.

But screen reader does not read the option value when tabbed or arrow keys are used.

Here is the sample code:

<div id="autosuggest" role="listbox">
   <div id="autosuggest_list">
      <button role="link">Value1</button>
      <button role="link">Value2</button>
   </div>
</div>

Any help would be appreciated !!