I have found that the binding must be done inside the summary app QVF script - it does not work at all inside a Must_Include of a QVS. Having bulky code in a QVF script in an enterprise environment is a seriously backward step. Up to now all our apps have just one line of code - a QVS Must_Include.
NOTE: Upon clicking this link 2 tabs may open - please feel free to close the one with a login page. If you only see 1 tab with the login page, please try clicking this link first: Authenticate me! then try the link above again. Ensure pop-up blocker is off.