I use Joomla! 3.6.0 and VirtueMart 3.0.18.
I have created Custom Field Type: Date with settings Cart Attribute and Cart Input set to Yes. In this case a calendar is shown in frontend and when the client chooses a date (es.Arrival Date) it's not shown nether in the cart nor in the order information.
If I change the settings to Cart Attribute - Yes and Cart Input - No than in the frontend the calendar is gone and automatically is shown today's date. In this case this date (today's date) is shown in the cart and order details.
How I can set this custom filed to work that the client chooses by himself the arrival date and this date is shown in the cart and order details???
Before doing anything else, update your Joomla!!!
You must update to Joomla 3.6.4!!
See
http://www.theregister.co.uk/2016/11/02/hurried_crims_target_30000_sites_to_pop_unpatched_joomla/
https://developer.joomla.org/security-centre/661-20161003-core-account-modifications.html
http://thehackernews.com/2016/10/joomla-security-update.html
Check if you have new Joomla users with administrator permissions - if so hackers have paid you a visit!