Hello Kok Kik, There are a few test cases which show that POI *can* handle multiple references to the same cell within one formula. For example: TestFormulaEvaluatorBugs.testSlowEvaluate45376(), TestEvaluationCache.testMediumComplex() and TestFormulasFromSpreadsheet. There is not enough detail in your description to distinguish your use case from what these tests do. Please try to reproduce the problem in a spreadsheet that you can upload (i.e. with no customer data). You can upload it along with the example code in a new bugzilla entry.
regards, Josh
