function classnum_changed(what) {
what.form.pkgpart.disabled = 'disabled'; //disable part_pkg dropdown
- what.form.submit.disabled = true; //disable the submit button
+ var submitButton = what.form.submitButton; // || what.form.submit;
+ if ( submitButton ) {
+ submitButton.disabled = true; //disable the submit button
+ }
var discountnum = what.form.discountnum;
if ( discountnum ) {
discountnum.disabled = true; //disable discount dropdown