In some cases, the wire gets tangled inside the dynamo, which makes installation difficult. This can be easily fixed by unwinding the wire all the way (rotate the key counterclockwise) while pulling the wire out of the dynamo. When the wire is fully out, start tightening it around your fork or seat stay by rotating the key clockwise. Make sure to keep the cable in tension while tightening - this will make sure that the wire does not get tangled up again.