[Plugin: Contact Form 7] no tag displayed on edit page

I just installed CF7 2.0.6, and it works with the default contact form (e.g., [contact-form 1 "My contact form"]) — sticking the tag in a page shows the form, and mail is sent correctly — but even with the default form, there is only an empty brown box below “Copy this code…” on the edit screen. Creating a new form has the same result, but I don’t know how to guess what the tag should be. I’ve tried viewing the edit page with Firefox 3.5.3 and IE 8. There doesn’t appear to be any text there — highlighting the line to copy any invisible text didn’t work. Looking at the HTML code confirmed there wasn’t any “tag” there.