Hi everyone. I've got a serious problem as a teacher with Greenfoot at the beginning of programming lesson. Greenfoot 3.1 (Windows & Windows portable) compiles correctly (and automatically after each code editing) class and project for 2-3 times and then it doesn't compile anymore. No error message. You can do whatever change you want to your code, no more automatic compilation happens. Even asking manually Greenfoot to compile the modified class (Compile button or CTRK + K shortcut) doesn't generate any reaction and compilation. So I've just tried to stop and relaunch Greenfoot + loading the same project. Here I've got the following message "The world class can't compiled. One of the classes may have an error, check them to initialize the scenario." Right after this I've checked code of all of the classes (Moon & Rocket -> it's a Lunar Landing very simplified scenario with just an animation of the landing, without user control). In order to simulate a change, I've just erased a few spaces + empty lines into the Rocket class (no change to the code). And then it recompiles again correctly... It's really a problem if Greenfoot sometimes compiles, sometimes not (more especially without reaction or error message : simply the previous version of the code is executed and not the last update version)... Very hard to test code for students and make demonstration for teacher. Any idea for being sur Greenfoot compiles each it is asked or has to do it? Thanks for attention, Laurent