Make sure you mute all the other strings while you are tuning. The vibration of one string may make the others resonate and make it difficult to tune. Also are you plugging into the tuner? Or are you tuning by the sound from your amp? Always plugin for a more accurate tune.. Also, I have found that it is easier to tune when I have the tone settings on the guitar set at max, the volume at max and on the front pickup (the one closest to the fretboard).