A date from the Date Picker is an invalid date!

Hi , I have a text input box with a date picker, I have set the format to DD-MMM-YY.

I also have set Date Validation on the same text input box.

On the page the date picker works well, but the date validation does not recognize the picked date as valid.

Note: if I set the format to YYYY-MM-DD in the date picker, the validation sees the picked date as valid, but this format is considered not the best for user friendliness. I have tried a few experiments DD/MM/YY also does not work, DD/MM/YYYY and many others do not work.

Any ideas on how to get DD-MMM-YY to be accepted.