a problem regarding facebook's message seen feature help !!?

[Dolphin]

So I sent my friend a message and then within a few minutes I saw that he had seen my message at so and so time but he didnt reply.The next day I checked again and then the seen at so and so time was gone.It was as if he had never read it ! Similar thing happened when i sent another friend a message.Any idea why the seen at so and so time disappears ?

[Mayar Mohsen]

Facebook is being modified so this will happen to you alot these days .. try to refresh your inbox just after sending anyone a message and the seen won't appear to you unless that person really saw your msg but didn't answer it