We have trying to install your widget on two websites, but both have the same problem. After submitting the emailaddress it comes back with a page not found error message - no matter if we left a 0, empty line, or pagelink in the field.
Also there is no submitting, so nothing happens.
Here is a link to the form, so give it a try.
After signing the page that the websites tries to load is:
What can this be?