contact form 7 – checkboxes don't show up

Hello,

I wanted to add three checkboxes to an existing contact form.

I did:
– generate tag
– choose “checkbox”
– added three options, one per line
– added the code in brackets to my contact form
– clicked “save”, at the top where the name of the contact form stands

But on my website the checkboxes don’t appear .
In the code I can see there’s the span-element for the checkbox element, but the span with the checkboxes itself is empty.

Did I save it “wrong”? But there’s only this one save button, so there are actually not many ways to do somethhing wrong…

(BTW: There’s only a drop down “generate tag” there seem’s to be no way to edit an already created tag.)