Lock/Unlock authorization

I have assigned lock authorization to 2 user ids (2 Maker ids). In the first user, I am able to Lock the infotype record i.e lock icon is appearing after i make changes to the record and unlock the same in checker user id.

But i am unable to lock the infotype record from the 2nd user id (Maker). I have assinged same role to both Maker ids. Kindly assist.