why the lopsided growth?

I built my scrubber on March 12th. The pics below are 5 days of growth. I have an area that literally has no growth other than a coating of brownish green on it and the other side is identical to it. In case you can't tell from the picture the lights are in the exact same spot on both sides. Are they too close to the screen? Is that what is causing the lack of growth?
http://i784.photobucket.com/albums/y...mboy75/as2.jpg
http://i784.photobucket.com/albums/y...mboy75/as1.jpg
http://i784.photobucket.com/albums/y...mboy75/as4.jpg
http://i784.photobucket.com/albums/y...mboy75/as3.jpg

Thanks in advance for the input!

Well, I would increase the flow over the screen and pull the lamps back a bit. You are photoinhibiting the algae, which is why only areas away from the light are growing.

You are not turning your lights off for 6 hours.

Ok, I'm sold. I have this scrubber on my 125 gallon African Cichlid tank and when I set it up on march 12th, my nitrate levels were 120 ppm. I was doing weekly 25-35% water changes and still couldn't get them under control. In a little over two months my nitrate levels have dropped to 5ppm and I would imagine they'll be zero in a few weeks. Thanks for all the info SantaMonica!