More and more insurance companies are requiring a valid (and often the correct) patient birthdate. If you are going to fake it, at least enter a birth date that is in the past (prior to the date of service of the session).
How to fix
You can edit the patients birthdate from the edit client form. The birthdate is located in the patient demographic section of the add / edit client form. Make sure you enter the birthdate in the format MM/DD/YYYY. Remember to save the client.