Set Nav Bar Image...not working

Hello...if anyone could help...i'm on dw 2004 mac osx and when i use the set nav bar image function for rollovers, it doesn't designate the jave...it leaves this line of code empty like this....onload=" "

When i choose the image for the rollover, i click ok and then if i open the dialog box back up, my selection is not there.

Any ideas???

Thanks a million