KA Lite unable to load exercises

I recently installed KA lite on Windows 7 Ultimate I already registered and created a user then I log in and everything was fine until I tried to perform a math exercise but the exercise did not load, later I realized that no other exercise was able to load. I just unistalled and reinstalled but the problem persists, I don’t have any programming knowledge and my native language is not english I’m just a high school student that wants study for his next exam, so any help is welcome, thank you in advance

PD: Im using Google chrome and Firefox