i got a 405 TD too. I advise that you preheat/glow for a while. If you open the bonnet and turn the key to preheat you will hear after about 10-15 sec. a click. Now try to start.
I usually count to 12 secs and then start.
Also you may try to squeeze the handpump (on the left side of engine block) and see if there isn't enough fuel getting to it. this may indicate a leak in your fuel system.
(I got a leak in the fuel system at the moment and trying to find it.)
johannes
April 2010