Piwik in Wordpress.com or blog.com blogs?

Hi to all!

I have use piwik in tumblr free blogs with no problem but I do not know if it is possible to use it in wordpress.com or blog.com free blogs.
In those blogs you can not use scripts so the only option (relatively easy) I see is the image tracking. I have put the tracking code in a text widget inside the blog but nothigs arrives to piwik.
I have try to put it in pages and in posts but the same, no analytic data arrives to Piwik

Has somebody integrate it in Wordpress o blog.com blogs? Where can be my error? The code I am putting in the widget is this:

Thanks in advance!

same problem on my side - wordpresss.com does not allow external plugins nore editing of files