How to fix a broken ARIA reference?

I have web page that has a broken ARIA reference upon doing a test. Specifically the aria-labelledby="myModalLabel" is showing an error. My understanding is there needs to be an id somewhere that references myModalLabel, but am not sure where if that's the case. Any help is appreciated!

<div class="modal fade" id="siteModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
    <div class="modal-dialog" role="document">
        <button type="button" class="close modal-close-button" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
        <div class="modal-content">
            <div class="modal-body">

                [pirate_forms]
                <div class="clearfix"></div>
            </div>
        </div>
    </div>
</div>