had a hanging light in diniing room. wanted to replace with a ceiling fan but junction box would not hold a ceiling fan. so went into attic pulled existing wire only about 6 inches up to remove from junction box. placed wiring in new junction box after it was secured. after installing ceiling fan , would not turn on. tried to replace old light that was there would not turn on. tested wiring and now have low voltage... ??? do i have to rerun the wiring from the outlet to the switch due to defective wiring? any other ideas?