Washer Jets

Ok here is a strange one.
My rear washer jet doesn't work. If i pull my wiper leaver forward to wash the rear screen the wiper sets off and the water squirts out of the front jets.
If i press the button on my wiper stalk to wash to front window, the water comes out of the front jets as it should.

Any one had this problem before and have a solution to it? :tonofbricks:

Think i have put this in the wrong section! :doh: