Got greeding and got myself lost...please help

I tried to incorporate the “Displaying Caption” with the XML Photo Gallery. I thought I got it all down, but it’s not coming out as anticipated.

Basically, I aimed to have the caption display as the mouse moves over the image. And the caption disappears when the mouse is not over the image. I thought it’s simple, but I fiddled for the whole week without any avail.

The caption for each respective image continuously appears.

Please look at my source code, and any suggestion is greatly appreciated.