All information is required for an accurate report. If you do not know your birth time (it's not on your birth certificate, you've asked people, etc.), take a guess and know that the data will not be 100% accurate. Contact the Local Records department for the state you were born and ask them to make sure the birth date is there and to send you the "Long Form Birth Certificate". Once received, come back and run your new report.
Drop me an email and let me know that the time isn't 100% accurate.