This is the button that I am trying to click on a webpage. All is does is open and menu with more buttons.

Code:
<a id="ctl00_ContentPlaceHolder1_TnBActivityList1_lbAddNew" class="actNewHyperlink" href="javascript:__doPostBack('ctl00$ContentPlaceHolder1$TnBActivityList1$lbAddNew','')">Add New</a>
I have tried a number of things and I cannot figure it out.

.Click is not working....