Hi there I have a Birt Report which read some stuff from a database. After that i want to increment a global Integer for every Detailrow that is loaded. So far i have initialized a global Integer with the following lines: importPackage(Packages.java.lang); reportContext.setPersistentGlobalVariable("minTotalPlus", new Integer(0)); After that i added the following line into a field in my detail row: reportContext.setGlobalVariable("minTotalPlus", new Integer reportContext.getGlobalVariable("minTotalPlus")) + 1); When i preview the report i get an "java.lang.NumberFormatException: null" which means that the global variable is null. Why is that so? How could I fix that?