According to :
No, it's at night, pitch black out...

You've left it alone for a full 24 hour cycle, and it doesn't come on
and stay on (according to the DD/2/4/8 setting) consistently on its own?

[I ask, because sometimes the electronics in these things will act
wierd if you try to "by hand" activate the sensor - time delays,
hysteresis etc.]

You may be seeing an overcurrent trip. Count up the number of fixtures,
and, after multiplying by the wattage levels of the lamp, is it less
than the rating of the transformer?

[Most LV bulbs/fixture/transformer "kits" use 4W bulbs, and can be upgraded
to 7W. High wattage units (10, 20 and even 50W) are available, but these
are usually pretty obvious (usually "pro grade" metal fixtures, sometimes
different bases, more serious enclosures to deal with heat etc).
Most "kit" transformers are around 60W.]

The other possibilities a

- short in the LV circuit. Try pulling all the bulbs (leaving one in)
and see if it still trips.
- defective transformer. The electronics in these things sometimes
fries.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.