Advanced Poll voting lock out implementation

I have installed Advanced Poll (nonSQL method) and have been using it in test mode for a little while. I have just 'turned on' the voting lock out feature. I used the admin panel to switch the value of 'check' from 'no checking' to 'IP table' with lockout timing 900 hrs. Now some users are being told that they have voted, when they haven't. When I checked the poll stats, no one had voted. I didn't think to check the [poll#].IP file at that time.

Since encountering the problem, I wondered if I needed to implement the optional 'cookies' code as well. So now, I have also added the include for the poll_cookie.php code to the beginning of the 3 pages where the poll appears. I changed the cookie timing from 96 hrs to 24 hrs. However, I changed the IP lockout to 2 hrs. I don't know which one will prevail.

Am I doing this correctly? I would like to be able to prevent site visitors from voting too often. However, I can't have them being locked out from voting, when they haven't voted in the poll.

Thanks for any help or advice.