I have put a new filter bag in my Kobold VK200, but the fill level display (LED display) is not showing a solid green light

It is possible that the sleeve of the 3-in-1 premium filter bag has not been cut properly.

Please open the VK200 filter cover and check whether the sleeve came off as it should have done when the lid was closed. If the sleeve is still intact, please remove it by hand and close the cover again.