I have configured the widget with all the correct information and keys and added it to my website. When I proceed to test it, I get an error message:
Sorry, we weren't able to sign you up. Please check your details, and try again.
However, when I check my list in Campaign Monitor, the email has been added successfully. I have tried this several times now, with different lists and keys, but the result is the same.
I have tried following the steps you recommended here http://www.leewillis.co.uk/debugging-problems-campaign-monitor-widgets/
but here I get no error at all.
Any idea of what the problem might be?
Thanks in advance.