Good news, #1 on Google in the morning, dissapear in the evening

On Oct. 8, when i Check the keyword phase"Toronto ebay deveper", my company comes out at #1, as shown in the picture.

However, when i came back in the evening, my site was gone.

This is google, sometimes it seems so wierd. But from the programmer's view, how can they guarantee the faireness of the ranking, how can they balance over 100 factors, how can they extract keywords information from each site, all this leads to highly complicated programming job. Sooo, it makes this happen.

Don't blame google on this, especially when you want to make some money out of google. Always keep your eyes on Google, make sure stay close to each move they make.