Well, the "Comments (optional)" field is for you to enter information if you wish. By itself, it has nothing to do with whether your snipe is successfully set up. When you have entered the item number, etc. do you click on the little button that says "Add!" just to the right of the "Comments (optional)" field? That's what gets your snipe ready to go. Try it and see.
Where do you click on "Snipe It?" Up in the right corner where the tab says "Snipe It Now?" That won't get your snipe scheduled. Let me suggest that you click on the tiny "faq" at the top of this page and look up "Snipe It Now."
Hang in there...we're making progress.