Javascript Works on Firefox / Chrome but not on Internet Explorer (v9) - repost

There is an order form which has an Add and continue button. If on Firefox or Chrome behavior is normal, it continues and cart can be added to or checked out. On Internet Explorer it never gets to the check quantity function. Have made sure javascript is working in IE and a few syntax differences to no avail. I did not code this and am not too familiar with browser differences issues between Firefox and IE. Someone that has done this before should be able to knock it off in 10-15 minutes.