No one answered but I had the same error using a widget with 2 parameters and a single datagrid in it. The datagrid path was defined through parameter 1 and adding the second caused the error. I had to put the datagrid in a dataview that specifically used parameter 1 as the context.
The entity path of dataview2 doesn't work with your current page setup. For future reference, take a screenshot of the regular view instead of the design view as the design view isn't as detailed in showing the page structure, even with the page explorer list.