Water leak in to boot

Hi all

I am hoping you can help me. My 200tdi has sprung another leak when it rains. I have taken the rear plastic strip off the thresh hold between the boot floor and the rear door and found water in the channel? With all the rain we have been having i am constantly drying the channel out. I thought it may be coming from the rear lights but the metal work is dry around the lights and around the boot seal and that too is dry i did this after a rain storm. Where else could it be coming in from???

Cheers all

mine leaks from the top of the tailgate door and drips onto the boot space cover. Don't suppose you know a fix for this problem ..?