A Google AdWords representative posted a thread at the Google AdWords Help forum. In that thread, Bindu, the Google rep, said that the recent marketing blitz from VistaPrint had the wrong coupon codes on them.
If you received a VistaPrint AdWords offer code, the code was misprinted. Specifically, the code was "accidentally abridged" so the code won't work. To get them to work, you will need to contact AdWords support - according to Bindu. Bindu said:
Recent VistaPrint Coupon Codes seem to be invalid because they were accidentally abridged. If you have received a VistaPrint code and it does not seem to work, you will have to write in to AdWords support and request the correct version of the code.
For more information on how to contact Google AdWords support, click here.
Forum discussion at Google AdWords Help.