problrm to Create a report from multiple table but using single dataitem in NAV 2013 r2

I want to create a report by using 'customer','customer ledger entry' and 'salesperson purchaser' table. I use CUSTOMER table as main dataitem. I take others tables in variable. Now I want to print  "Customer no", "Customer Name", "Salesperson Name", and "amount" in a report. I got all fields except "Amount" field. If I take "CustomerLedger Entry" table as main dataitem then there is no problem to print amount.. please solv this...