BY TIM WILLERT, Staff WriterSchool districts across Oklahoma could recoup as much as $18 million in state aid for the current fiscal year, a revenue stream state Education Department officials say has been miscalculated annually for more than two decades. State schools Superintendent Janet Barresi acknowledged Thursday during her last regular board meeting that a calculation used for state funding to districts that accounts for ad valorem tax revenues had not been applied by the Education Department since 1992, despite being required by law. Barresi also said the Oklahoma Tax Commission had not supplied the necessary data to the department over the same 22-year period, data she hopes can be calculated by Jan.Read more on NewsOK.com