The method ZCiCal::fromSqlDateTime() is deprecated but the suggested replacement method ZDateHelper::fromSqlDateTime() does not exist.
class ZCiCal {
...
/**
 * Format into iCal time format from SQL date or SQL date-time format
 * 
 * @param string $datetime SQL date or SQL date-time string
 *
 * @return string iCal formatted string
 * @deprecated Use ZDateHelper::fromSqlDateTime() instead
 */
static function fromSqlDateTime($datetime = ""){