New installation trouble
 

I am installing a new low voltage outdoor lighting system. There are 5
x 20w spot fixtures and one Malibu Lighting 200W transformer.

After installing the 5 lights, I laid out the 12-2 supply. The
furthest lights (2 on one post = 40w) are about 70' from the
transformer, and I hooked them up first.

With only those 2 lights attached, the transformer is cycling on/off
every 20-30 seconds.

The transformer, fixtures, lamps, cable, and connections are all new.
I took pains with the connections.

What am I missing? Please help.