Selected tab not getting highlighted

When I click on my second tab, the page and data load just fine. But the tab does not get highlighted. The gray highlight is still on the first tab.

<div runat="server" id="wftabs_tabs" class="tabHeader">
    <input type="hidden" value="0" runat="server" id="ActiveTabIndex" />
    <ul>
        <li><a id="index" runat="server" href="index.aspx">Environment Checklist</a>
        </li>
        <li><a id="envUpdateReview" runat="server" href="EnvironmentUpdateReview.aspx">Environment Update Review</a>
        </li>
        <li><a id="datasets" runat="server" href="datasets.aspx">DataSets</a>
        </li>
    </ul>
</div>