Date Availability Checker

Hi,
I’m looking for a simple solution to be able to use a form entry to check if a certain date is available or unavailable. The user wouldn’t see any availability information, such as a calendar, they would simply fill out a form and depending on what date they select they receive either a ‘Date is Available’ or ‘Date is Unavailable’ response. Sounds like it should be so simple but I’m having trouble.

Thanks in advance.