Income booking

Dear All,

Suppose Mr A has a Building Containing 10 Shops, out of 10 Shops 2 Shops are sold out.

Maintainance of Building is being done by Mr A and as per terms Mr A charged mainatainace Cost from all Shops.

In case one shop which has sold out is vacant and maintainance charges is not being paid by owner as per terms for last 18-20 months.

Should Mr A book income of maintainance charges as in actual he is not receiving the money?