Failure to show pictures in guestbook

Hi, I just made a new guestbook, but there is a problem that all the photo and graphic doesn't show when people go in to the guestbook. When I click to the next page, the pictures did show up on the second page, then when I went back to the first page, all the pictures back.

How can I fix the problem?

Thanks

you need to set the base_url variable in the config.inc.php file.