I'm doing gateway cloning, I'm setting up LR reaction of entry clone with destination vector PKGWFS7 containing Ccdb gene at insert site. Ccdb is inhibitor of DNA gyrase, in most of the cloning we insert our gene in place of ccdb gene present at insert site in the vector, and we get the colonies next day after transformation. But when we do colony pcr, we don't get most of the colonies positive for insert, then how do those negative colonies grows on plate containing antibiotic and ccdb gene in vector? What is the reason, if they don't have insert, why we see those fake colonies?