Scrollbar not visible in <div> in WebView

I have an Html file containing a scroll section. When I add this HTML to the WebView, it does not show the scroll bar for this div.

I have code in an html file.

// some Html code


<table style="border: 3px solid black;" align="center">
 <tr>
<td ><div style="width: 100%; height: 50px; overflow: auto;  padding:0px; "> <div>
  put returns between paragraphs
► for linebreak add 2 spaces at end
► _italic_ or **bold**
► indent code by 4 spaces
► backtick escapes `like _so_`
► quote by placing > at start of line
► to make links
<http://foo.com>
 [foo](http://foo.com)
► basic HTML also allowed

 </div></td>
</tr>
</table>

// some Html code

When I add this Html file to WebView in xml file.

Xml code ...

// some HTML code

<RelativeLayout
    android:id="@+id/webLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@+id/buttonLayout"
    android:layout_below="@+id/titleLayout" >

    <WebView
        android:id="@+id/webViewMain"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </WebView>
</RelativeLayout>

// some HTML code

It works fine, but does not show the scroll bar for this div that has been added to the HTML file