Bootstrap Datepicker - setStartDate issue

I'm trying to change the starting date of a bootstrap datepicker input field.

I have 2 fields both are datepickers.

• actie_begin
• actie_end

When I change actie_begin I want the startDate of actie_end to be set to the value of actie_start.

here's the code I wrote

<script type="text/javascript">
    $(".actie_begin").datetimepicker({
        format: 'yyyy-mm-dd',
        startView: 'month',
        minView: 'month',
        autoclose: true,
        startDate:'-0d'
    });

    $("#actie_end").datetimepicker({
        format: 'yyyy-mm-dd',
        startView: 'month',
        minView: 'month',
        autoclose: true,
        startDate: '-0d'
    });


    $( ".datepicker" ).on('changeDate', function (ev) {
        $('#actie_end').datepicker('setStartDate', $("#actie_begin").val());
    });
</script>

The datepickers work, but when I try change the date on actie_begin I receive this error:

Uncaught TypeError: Cannot read property 'apply' of undefined

The values get set and I can pick the dates, but the startDate on actie_end does not work.

How can I solve this issue?