When a click occurs outside of the targets of the campaign, it is considered invalid. That means it is not in the right country and/or on the right device and/or with the right carrier, etc.
For example, if a campaign is open only in the United States and the user clicks on the link from a device in the United Kingdom, this will be counted as invalid.
An invalid click displays an error instead of redirecting to the landing page of the offer. By default, this error page will then redirect to an offer corresponding to the user parameters.
You need to make sure to send traffic corresponding to the target of the campaigns to the offer you display.