Tail lift not going up

Hello guys really need some help! 2000 Renault midlum 150 race truck / lorry .. Im getting a click when pressing up button on the tail lift .. Ive lowered it down and cant get it to go back up!! Click , Click , click.. Frustrating.. But no motor noise engaging at all to be able to put the tail lift up.. Is there an hydraulic oil level that may if too low stop the motor / lift working ? .. Any ideas what it might be ? Its a bit of an emergency because the door is modified full length for a rally car to go in back & has a winch attached to it and the weight of tail door is hanging on the winch cable and its going to end up pulling the winch off the bench on the inside and busting through the back door ! Thanks!