Sound in Dreamweaver MX 2004

At times when I am inserting a wav sound on a image and I try to add the
behavior of onMouseOver, I don't get that as an option (there are only three
options and one of them is onLoad). I haven't been able to determine why this
is happening some times but not other times since it doesn't seem that I am
doing anything different. Does anyone have any ideas as to why this is
happening?

Also, how do I create a background sound? I tried a midi and it loaded (that
was the behavior I used) but I think it was the Quicktime screen that came up
instead of the IE browser.

Any suggestions would be greatly appreciated.