The first step is to make sure that the script is still installed in your pages.
Open a page of your website in a browser.
View -> page source?
ctrl + find for "opentracker" and make sure that the script is still installed in your pages. It happens quite frequently that the script is inadvertantly removed when pages are updated, etc.
This is the most likely cause, if you stop recording traffic.
If you find that the script has been removed and you need to have your script resent to you, you can resend yourself your original welcome email with your script. You do this on the 'site management' page.