Hierarchical Flex Grid

Hello,
I've a problem in using hierarchical flex grid,
when i'm repainting the grid with new data, the grid becoming a mess.
i cannot move through different cells, some cells are not dispalying the data.
my grid has got 3 bands. for example, suppose the grid initially paints with 10 rows.. then i'm requerying and that returns 0 records and the grid will become blank, again i'm querying and this returns some rows and the grid will be painted with new data, but this time i cannot move through the different cells..
it would be greatful if anyone can help me out of this problem. You can even mail me in [email protected]

thank u