After upgrading to OS X Yosemite, I have run into a problem with File Renaming on Import. The numbers are not sequentially following the original file number order from the SD card by way of a card reader. I'm using a Nikon D7000. I've never run into this problem and have been using Lightroom since V.1. I tried trashing the imported Picture folder, and reimporting. Each time, the random order changed. I got around this possible bug by copying the .jpg files from the SD card to a folder on the desktop, then on Import I selected the desktop folder as Source. At this point the photos are now imported sequentially without error.