>>Try the query without the indexes and without set order. That should give you the correct result. Then see about adding the .idx via SET INDEX not via SET ORDER
>
>I put set order to and got
>
>Found a mismatch on I909648COL cRate = 0 laArr[1]= 0.094859333
>Found a mismatch on I909609COL cRate = 0 laArr[1]= 0.100000000
>Found a mismatch on I909656COL cRate = 0 laArr[1]= 0.100000000
>Found a mismatch on I808204COL cRate = 0 laArr[1]= 0.100000000
>Found a mismatch on I808205COL cRate = 0 laArr[1]= 0.100000000
>Found a mismatch on I807227COL cRate = 0 laArr[1]= 0.100000000
>Found a mismatch on I808130COL cRate = 0 laArr[1]= 0.087330233
>Found a mismatch on I808228COL cRate = 0 laArr[1]= 0.067779691
>Found a mismatch on I808229COL cRate = 0 laArr[1]= 0.067779691
>Found a mismatch on I518767COL cRate = 0 laArr[1]= 0.100000000
>
>This is strange since these Inv_No + Salesman do not exist in the table. I've tried to do select and seek in command window and they returned empty results.
>
>Somehow SELECT SUM() finds wrong records. I re-built index Com_Inv earlier today by deleting it first.


You did not do what I said. Why is that? I said to turn off the indexes. You made no indication that you did that.

Rushmore does need indexes, but VFP and VFP-SQL can operate without them.

Be scientific. Get the correct results from the DATA. Turn off all indexes. Get rid of anything that may be contributing to the problem. Focus on the data structures. Use data that you can visualize clearly. Using live data that exhibits a problem is much harder to diagnose than a small sample that exhibits the same problem.