I have a for with a multi-select field linking people with sessions they have taken. When I use the built in search function in the report to search for a people who have taken a session containing "Y" I get the expected results but if I search for people who have taken a session NOT containing "Y" I get the wrong results. 

When I search for contains Y I get 77. When I search not contains Y I get 1416 results. I have 1427 total entries in the form. I expect the not contains Y search to get me 1350 results. The not contains search is either not doing it's thing correctly or I'm making an error. Any help?

Cheers,

Rene