I always give the frames a real good wash on the first clean, there will be lots of dirt in all the cracks, it may also help to go over the windows twice, if they're lead lites it can be even harder to get results first time, it will take a few cleans before you get perfect results every time, take longer to rinse the first few times too, takes more water at first but pretty soon you'll get results, stick with it m8!