DNA binding proteins ELISA - need suggestions (Jul/19/2008 )

I am trying to optimize DNA binding using colorimetric method. I have antibodies for the DNA binding protein. After immobilizing the DNA to microtiter wells and addition of the DNA binding protein the complexes will be measured using TMB substrate. My problem is I am getting very low absorbance values. I am using 400ng 500bp DNA and the protein 10ng to 80 ng. I can see a saturation at 40ng. But the readings are very low. Please suggest

thanks in advance

HI transposon,
can you please tell me how are you coating your DNA to ELISA plate
give me the reference if possible
may be the method you are following is allowing you to capture only a small fraction of DNA to bind to the plate
Leelaram