Two datasource in a grid

Problem with ranges for Grid with fields from two datasources

I have a form and two datasources (A and B), which are joined (A is parent and B is the child)
and a grid with fields from both datasources.(Datasource of the grid is A)
If I add a range to A, everything is fine,the range is executed. But if I add ranges to B, these ranges are ignored.
Any idea why this happens?

Is LinkType on the child datasource set to InnerJoin?

Yes. Its inner join

How do you add the ranges and what exactly is the result? Do you see your ranges on the Query tab in form setup?