When calculations don't turn out the way you expect, Profitability and Cost Management offers several tools to help you locate and resolve the problem:
Rule Balancing features -- Show flows of funds into and out of dimensions
Rule Data Validation report -- Shows source and driver data targeted for each selected rule
Execution Statistics report -- Shows runtime statistics collected for the selected calculation job following the end of the job
Program Documentation report -- Shows rule sets and rules plus rule definitions
For details, see Troubleshooting Calculation Issues.