How to get the correct standard BSA curve for my protein estimation?

I have purified my protein and want to estimate the amount. The plot I am getting is half of the value my senior is getting. The difference is I am using a kit (Genei TM) for Bradford's assay. But he prepared his own reagent. There might be a difference in reagents, which I can understand, but the amount of protein should be the same and I am only getting half the amount of protein as earlier estimated by my senior. Please suggest what I should do. The dilution I am making is not wrong and the expiry date of Bradford's reagent from the kit is Dec 2013. So how should I proceed now? The slope value he (senior) got is 0.0196 and the R value is 0.99 from his own reagent. My slope is 0.009 and my R value is 0.98