Landscape lighting

[paulson76]

I have a 200 watt transformer with a 12V and 15V terminal. I have 6 fixtures all in a line that take 9.8 Watts to power. When I hook these up, the first 2 lights work great, The line passes under a sidewalk through a conduit, The next 2 lights will work until I try to add more fixtures then they just flash. The last 2 fixtures don't seem to get any power. I am using a 12awg wire. The first wire is 100 ft and takes me to the 5th of 6th fixtures then I have spliced in an additional 10 ft of the same wire to the last fixture. I've mixed and matched the lights so I know they all work.