There are scenarios where QTP/UFT may recognize some Web Forms grids as WebTables instead of WbfGrid test objects.
For this the following article has been created:
Note: There are known issue about WbfGrid and QTP 11.0. QTP is able to recognize WbfGrid object in IE 32 bits, but same object is recognizes as WebTable in IE 64 bits. So, Users can either continue using the IE 32 bits version or upgrade to UFT 11.5x.
Hope this helps.