The Elisa Assay is competitive, my final values are about 40 pg/ml but the sensitivity of the kit is 70 pg/ml although the reads fit into my calibration curve.
We did that extra Step, and the reads fall within the calibration curve, but in terms of sensitivity, the reads are below that point. As far as I understand below the sensitivity the reads might be unclear that the reads come from the sample or the background, but I am not sure.