CoolScience

I need help with my yeast 2 hybrid screen:( Can I get many false positive (blue) due to my own reagents? I am looking for interactions between several genes. I have started by checking whether my Yeast strain auto-activated. And surprisingly it does! I have bought and tested few strains and all auto-activate! I am now questioning my X-Gal, LacZ, and filter/nitrocellulos papers! Can I get soooo many false positive because of my reagents, or it is true that my yeast auto-activate on their own?