[rules-users] how do I add not exists contraint in dslr

Hi, I have been trying to add not exists constraint in dslr but its failing to parse the dslr. Here is what I am trying to do in DSLR [when][][*Tt*]here is at least one {entity}= not(exists {entity}: {entity}()) If I simply use the exists constraint here then it works well. But then after adding not to it, its not getting parsed correctly. error I am geeting is: [10,27]: [ERR 102] Line 10:27 mismatched input ',' expecting ')' in rule "Rule1" in pattern Person not sure whats going wrong here, if it is expected to work this way? thanks, -m