Contract to sell

Dear PAO,

My brother and I are co-owners of a building being rented by Dean. Eventually, my brother sold his share to me. I paid him half of the price agreed upon and the remaining balance will be paid after one year. He promised to execute the necessary deed of sale after full payment of the total consideration. I found out my brother is still collecting his share in the rent from Dean so I confronted him. He claimed he is still a co-owner of the building so he is entitled to his proportionate share. Is my brother entitled to his share in the rent after our agreement?