Sorting and dynamically setDataModel

There seems to be some kind of bug when I click on a column header (sorting data on a column) then when I set a new datamodel dynamically (using Active.XML.Table). It then displays empty rows, sounds like the sort index is not updated, the effect is very noticeable if the second datamodel is nearly empty.

Does anyone know some kind of workaround or where I should start in order to fix this (i m new to using the grid).