About Oracle global temporary tablesand Axapta

We want to use Oracle global temporary tables instead of Axapta temporary tables because it’s faster (Oracle maintains data in the sort area of the user in the SGA versus Axapta temporary table is maintened in a file) If I create a Axapta table and then drop Oracle table and recreate it as global temporary, Axapta never fill the table, it’s always empty… How des it works ?