Remember to check first that the CO2-cylinder is attached properly. If you still suspect that the cylinder is empty, here are some tips to check if you need to change the cylinder:
1. When you press the carbonation button and no bubbles appear
2. When you have carbonated the water but wate is not fizzy
3. The carbonation button feels loose and there carbonation process makes no sound Check here for instructions on how to change the CO2-cylinder.