Peugeot 807 Rear Wiper Wash problem?

I have problem with rear wiper wash. The water does not come out from rear wiper. I have checked the tube and everything else but nothing is loose or any holes present.... One strange thing. When I pull stalk for front windscreen wash, it works very well with water come out of wiper but when I want to use rear wipe wash and turn notch to make water come out of rear wipe, it also does the front windscreen as well?? It should not be like that. Can anyone advise me what shall I do next?