I copied my lightroom library that is store on a external drive to another portable USB 3 drive. They are located in a folder that is broken down into several sub folders. I dragged the main folder and drop the files onto the portable drive then navigated to my home folder picture where I copied the lightroom folder. When I open up library i can see the photos but I still get the exclmation point saying it can't find the photos. Is there a quick easy way for it locate the photos?