hiding columns in datagrid not working



I queried a series of fields from a database and passed into a datatable.
Then bound this to a datagrid. I need to hide 2 of the colums. This doesnt
seem to be working the standard way. (with datagrid columns hide). When I
query for number of columns in datagrid I always get 0 no matter what, even
after showing all the columns. I must dynamically build the table after page
post (I pass in parameters to define the table I'll be querying) so I dont
know the columns up front. Any ideas?