Filtering row issues with different datasource configuration

Hi,

I am trying to add a filtering row to my grids and I've come into some issues with how my data is provided to my grid.

I created an example showing the issue I am having : http://dojo.telerik.com/oSat/2
If you look at the javascript console, it is trying to access the object value but the one passed is of a Group.

Something weird I found while trying to isolate the issue, the above works if I pass a javascript object to the datasource parameter instead of a datasource object ( http://dojo.telerik.com/oSat ). But in my case, the datasource is created before it is attached to the grid so I cannot really use that fix.
The documentation says that if you pass it a javascript object, it just creates the datasource for you but there must be something done different?

Thanks