Inside my trigger method i wrote below code:

public void OnBeforeUpdate(List<Account> newAccList ,List<Account> oldAccList ){
        Approval.UnlockResult[] lrList = Approval.unlock(oldAccList, false);
        system.debug('-----lrList-----'+lrList);
}
In debug log below ,I have no errors and isSucess flag set to true, but my record is still locked :
----lrList-----(Approval.UnlockResult[getErrors=();getId=00163000004DNG6;isSuccess=true;])

Has anyone used this new feature of winter 16 sucessfully?or can anyone advice why it is not working for me?
 

 Inside my trigger method i wrote below code:

public void OnBeforeUpdate(List<Account> newAccList ,List<Account> oldAccList ){
        Approval.UnlockResult[] lrList = Approval.unlock(oldAccList, false);
        system.debug('-----lrList-----'+lrList);
}
In debug log below ,I have no errors and isSucess flag set to true, but my record is still locked :
----lrList-----(Approval.UnlockResult[getErrors=();getId=00163000004DNG6;isSuccess=true;])

Has anyone used this new feature of winter 16 sucessfully?or can anyone advice why it is not working for me?