Im having a problem with my ligation and not sure how to proceed... My vector has two Pci I cut sites and i used it to cut out a fragment from my vector that i did not want there. I then used thermoscientific ligation kit to self circularize my vector. However after plating onto an Xgal IPTG induced amp plates, i either get no colonies or just light blue colonies. My vector is a pTZ-57RT plasmid with an insert, so shouldn't i only be getting white colonies because the beta galactosidase gene was already interrupted with my insert? did i need to do blue white screening for my self circularization experiment. also how could i get more colonies. My transformation positive control plate was fine so i don't think transformation efficiency was a problem. I used 20 ng of DNA the protocol said between 10-50 ng of linearised DNA.