Java-Script error on clicking "Donation made in honor off" checkbox

I've enabled the "Donation made in honor off" option, and can see it now on my donation form.
However, when I click the checkbox on the form, nothing happens on screen -- the radio buttons and text fields that should appear do not appear.
Checking the Console, I've got a Java-Script error:
Any suggestions on what might be going wrong?

edit: I'm seeing an additional JS "TypeError: $(...) is null" error from another unrelated script that might be crashing java-script. But it only occurs when I resize my browser window. You can see my test form at www.sttherese.ca/jdontest .

Hi James,
Could you please submit ticket and send your site url with super admin account. I will check the problem for you.
Thanks
Dam