A Rule step based on someone not performing an action doesn't work for something like this; instead, you'll want to set up the original Sequence, assuming that people will not do the action, and then create Rules to remove them from that Sequence when they take the action. For example. Have a Sequence that sends out an email with a link to your site. 10 Days later have a second step, an email step in this instance, set to follow up with people who didn't click the link. Next, create a global Rule that removes them from the Sequence if they click the link. Because the rule is a global Rule, it will fire globally (regardless of when they actually click the link), so as long as they do it before that second email is set to fire, they won't get the follow up bugging them to check out your webpage.