All lenses have a minimum focusing distance. If you’re closer than the minimum focusing distance, the camera will hunt for focus for several seconds, and then give up. All you can do is to move farther from the subject and re-focus… or add an extension tube, which will allow you to focus closer. To get great close-up pictures, however, you’ll need a true macro lens. Unfortunately, because true macro lenses are always prime, they aren’t good general-purpose lenses. My advice: wait until you get frustrated with your primary zoom because you can’t focus close enough, and then add a 100mm or 150mm macro lens to your collection.