Toggle collapse not working in IE9

[Wesley Chin]

Hi there, 

I have implemented the collapse on one of my div's, works perfectly in Firefox and Google Chrome, but not in IE9 although the display is perfect in IE9.  Any help please?

My code is shown below:

<div class="well">

                    <div class="row">

                        <div class="span1"><button id="btn1" onclick="toggleBtn1()" class="btn btn-primary" data-toggle="collapse" data-target="#well1">+</button></div><div class="span10"><h3>Opportunities Split</h3></div> 

                    </div>

                </div>

                <div id="well1" class="collapse">

                    <div class="well">

                        <div class="row">

                            <div class="offset1 span4" id="oppSplitPieChart1_div"></div> <div class="offset1 span4" id="oppSplitPieChart2_div"></div>                    

                        </div>

                        <div class="row">

                            <div class="offset1 span4" id="oppSplitPieChart3_div"></div> <div class="offset1 span4" id="oppSplitPieChart4_div"></div>

                        </div>

                    </div>

                </div>

Regards,
Weslley