After you've installed the Modal Forms pixel on your site, you will want to confirm that the pixel is present on your website.
Next, you will need to find the pixel in the code.
A quick way to search for the pixel is to press Command + F keys on mac OR Control + F keys on windows which will bring up a search bar.
In the search bar type "app.modalforms.com". If you have Modal Forms installed on your page, you will see code similar to this:
Make sure that you only see one instance of the script in the code. If you notice that it is installed twice on the page, you will want to go into your code to remove one of them, otherwise it won't trigger properly.