iTunes doesn't recognize songs added from older Mac

I tried to add songs from my old iTunes library to my latest iMac but iTunes doesn't "see" the added files; however, if I go to the Finder window and click on the individual songs, iTunes plays them and then they appear in my iTunes (in my library.) Do I have to click on every one of my old songs to get the newer iMac's iTunes to recognize them or is there some way to batch import them?