There is an error in calendar-setup.js that prevents the setting of an initial date for the calendar. Go to line 159 and replace the code:

if (dateEl) params.date = Date.parseDate(dateEl.value || dateEl.innerHTML, dateFmt);

with:

if (dateEl && (dateEl.value || dateEl.innerHTML)) params.date = Date.parseDate(dateEl.value || dateEl.innerHTML, dateFmt);