Can't upload a file with Sahi / Mink / Behat in a Symfony2 application

Use absolute system path to which Sahi server has access.

Is the url to which the form is posted different from the url of the web page? _setFile and _setFile2 take a third parameter which can be configured to point to the action URL (the url to which the file should be attached by the Sahi Proxy) http://sahi.co.in/w/_setFile