Filtering Grid using XPATH

Hi,

I am using version 2.0 standard edition. When I am filtering records in the grid then sometimes it happens that all the records does not appear in the grid. Some of the records appear and in place of the missing records i see blank column without any data in it.I am doing filtering using XPATH expression. I am retrieving all the records in the XML from the server and populating whole of the grid. Now at the time of filtering I am using XPATH expression to filter the records meeting the criteria from the XML fetched from server initially to populate the grid. Can somebody help me out in this. Is this some problem relating to filtering using XPATH.

Thanks,
Piyusha