Ensure that the destination panel is open on the right of the import dialog and that you have read & write permissions on the folder you are copying into. The full file path should be shown at the top.
If that makes no difference, launch Finder and go to Applications. Launch the Image Capture app and if your card is recognized copy the photos into a named folder or new folder. Then bring them into Lightroom using Import >> Add (rather than copy)
Thanks I have now got them on my computer and want now can ADD them to lightroom but I can't MOVE through lightroom on to my external hard drive. Any Ideas?
Your external drive is probably formats for Windows (NTFS) which a Mac can read from but NOT write to so you can not move or import files to the external.