Selecting timepicker slider changes date

[awthird]

I am using air-datepicker for the default jQuery datetime widget. I define startDate to set the initial date for datepicker, and add timepicker. When the popup window opens, it shows the correct date and the time. If I select either the hour or minute slider in the timepicker, the date spontaneously changes from the default to the current date. How do I change the time on the default day without changing the date?