How to handle popup in IE using watir-classic

Question

I'm trying to click on close but it is not clicking.

below is my code:

b.button(:class , "close").click

HTML code:

 <div class="modal-content alert-">
<div class="modal-body">
<button class="close" data-dismiss="modal" type="button">
<span aria-hidden="true">×</span>
<span class="sr-only">Close</span>
</button>
<div>
<h4 id="daModal1493381568370"/>
</div>
<br/>
<p>Invalid driving experience, please call us at 666 55555 for assistance</p>
</div>
</div>

Note: First i'm trying to check alert exists or not then clicking on close.

b.alert.exists?# i'm getting false
b.button(:class , "close").click

And also tried:

b.span(:class , "sr-only").click