Yapta enables travelers to track pricing on specific flights.  Yapta does not track all flights between a given origin and destination – unless you tag and track them all, which is something that you are totally do!  Various flights will yield different prices.  If you’re using Yapta to shop for the absolute lowest price with little regard for departure times or layovers, tracking multiple flights is highly recommended to help ensure that you’re aware of the various flight options and prices.