The sum should adjust to the value of the first three records. Can you post a sample application, using inline load, to demonstrate the issue you are having.
You are using Expression Total as your total mode. Therefore, your column totals are calculated based on the expression value for each dimension, not simply a sum of the values in each row.
For example, in your application if you select Type A and C the avg(Value) for A is 15 and C is 27. The avg(Value) column total is 19.8 (ie. the average of all A values 10, 15, 20 and C values 4, 50).
If you want your total columns to simply sum up the values in each row, change the total mode to Sum of Rows.
The total modes can work the same is some cases, depending on the aggregation funcition used. The sum function will sum all values for the selected dimension which works the same as summing the results in each row. As shown in my example, functions such as avg and max will return different results based on the total mode.
