Man Lion's Regio L - Haldex Consep dont work

Hello,

I have a problem with a Man Lion's Regio L. The automatic drain is not working on the new Haldex Consep Condenser/Separator. I can measure 24 volts. How does this thing work, Electricaly? On other buses, the drain opens every minute, but here it doesn't. Thank you for your help.