Yep, it sure does! First, just to make sure, the noise is a hum rather than pops and crackles, correct?
The outer braid of the cable (you are using coax type of audio cable correct?) is grounded at the amplifier end only. The rest should be floating. If there is a second ground connection along the way, you have formed a ground loop that can induce noise into the circuit. Also, make sure that the Guitar and amplifier jacks are wired the same way. The tip of the plug should be hot and the rest grounded. Therefore, the spring of the jack that the plug’s tip pushes against and then snaps into the indent of the plug should be hot and the other connection (the part the sleeve slides into) should be ground. Inside the box, there must not be a break in the shield from one jack to the other. If you have not tested it do so. The best way is with an ohm meter. If you haven’t got one, pull the end off a flash light and connect one wire to the case and another one to the battery. If the flashlight lights, you have continuity.