ADVANCED POLL - works on one page not another

I started using Advanced Poll several months ago and everything was great up until a few days ago when suddenly the poll stopped working. When a person comes to the page, the poll shows up (even if they already voted) and then when they vote, it goes to a 404 error page instead of displaying the results.

In trying to fix this problem, I loaded a new poll onto a test page on the same site and it worked, so I changed the test page name to index.html (the test page was called test.html) and it wouldn't work again. Nothing else was changed - I simply changed the name of the page.
It works on the test page but not the index page. What can I do to put the poll back on the index page?

Review the instructions in this forum for making the poll work with .html page. Otherwise, your page extension needs to be .php.

Web page is .html, .shtml:
http://proxy2.de/forum/viewtopic.php?t=4736&highlight=shtml
http://proxy2.de/poll/demo_5.shtml

Both pages are html pages, and it works on the test.html but not index.html. I also tried it with index.php and the same thing happens.

Check the base url.

They are both relative urls on the same website... both using the same base url.