When you have a fixed asset disposal by sales, if exists depreciation, depreciation is reversed and sales is posted. For any reason, customer does not know that depreciation exists. Idea is: Warning message should inform that depreciation exists for the same period when sales takes place reversing depreciation amount. +++++++++++++++++++++++++++++++++++++ For example. a. Acquire fixed asset in January b. Depreciation from January to March (next year or anytime) c. Disposal by sales last day of March. With this scenario, sales is posted but depreciation of March is reversed. A warning message should appear preventing depreciation reversal for March.