Netscape 4.7 error -- gm has no properties.

[tv2n]

I keep getting this error msg whenever I update the mmenu.js file.

gm has no properties.
JavaScript Error:
http://www.virginia.edu/pswebtest/DEV/T ... b/mmenu.js, line
486:

Does anyone know why? and How I can fix this?
URL to testing site:

http://www.virginia.edu/pswebtest/DEV/Thuy/psweb/

thanks.

[tv2n]

In case others might get the same error msg.
I found that if I put the
"<SCRIPT LANGUAGE=JavaScript>
PlaceMenu("mainmenu")
</SCRIPT>" in its own table/cell then it will work.