What are some reasons why form submission fails in IE9?

Question

Angular

There is a form

<form name="searchForm" id="search_f" ng-submit="submitSearchForm()" novalidate data-ng-controller="searchFormCtrl">
...
  <button ng-disabled="!lastNameValidate() || !snilsValidation() || !existSelectedSources() || !dateFormatValidation()"
                            type="submit"
                            class="btn btn-primary btn-md"
                            title="Произвести поиск по введенным данным">
                        Найти
                    </button>
</form>

And everything seems to be working fine, but in IE9 the submit sometimes doesn't work. What could be the problem? Maybe someone has come across something similar.