I have a databound grid that I have set up just like in your expandgrid example. It is a databound grid. I am on version 2.0.0.4, the grid is not expanding like it is suppose to. Not by clicking on the plus or in code.
I can see the data for the parent in the grid but since it will not expand not the child. The data is in the child table and the keys are correct.
I have attached a snippet.
snippet_3810.zip