DQM "use as filter" attribute

Hi,

I want to filter some customers using the "advanced search" DQM screen using a custom attribute (since the attribute I need is not included in the attributes list). I have created a PLSQL function to filter the customers at the acquisition moment. My function returns "NULL" whenever there is a  NO_DATA_FOUND exception. Is that OK, since I want to filter the customers right from the acquisition moment?.

Then I have assigned the new attribute to a match rule and defined the usage as "use as filter", without any display sequence, since I don’t want to display it. I have recreated all the staging data and cleared the cache memory. For some reason my new attribute is displayed and the data is not filtered, as if my function has not filtered any customer.