vTiger 7.1 - List Conditions - Not Equal To doesnt appear to be correctly identifying records

When creating a List in Contacts, we are adding a Condition using Organisation Name. (related field to Accounts module) If we specify Organisation Name EQUAL TO 'Name' - this correctly shows us all the Contacts which are related to a specific Organisation.

If we change this condition to Organisation Name NOT EQUAL TO 'Name' - we would expect this to show us the opposite of the results from the first condition, however its not showing us Contacts which have NO Organisation Name.

e.g. Contact A -> Organisation Name = 'Test' Contact B -> Organisation Name = ''

Condition = EQUAL TO 'Test' shows us 1 record (Contact A) Condition = NOT EQUAL TO 'Test' shows us 0 records - but Contact B does NOT EQUAL 'Test' and so should be displayed as well.