Approval cycle

Summary:

I did an approval cycle which if one of these grades happens not goes to a specific person but when i test after i did this condition it stills goes to this person which his position is Employee relation manager so is there anything wrong I did. 

((Worker's Current Assignment. Grade Code!= "APC SAUDI.A") OR (Worker's Current Assignment. Grade Code!= "APC SAUDI.M") OR (Worker's Current Assignment. Grade Code!= "APC SAUDI.N") OR ((Worker's Current Assignment. Grade Code!= "APC SAUDI.O") AND (Worker's Current Assignment. Business Unit == "APC HQ"))) goes to representative "employee relation manager"

Content (required):

Version (include the version you are using, if applicable):