In Dragon Ball GT, we are told that the negative energy that popped out of the dragon balls of the earth was created as a result of wishes that were made since the beginning of the Dragon Ball series. For example, a shadow dragon was formed when Oolong wished for underwear.
In Dragon Ball Z however, we know that the earth's dragon balls were gone after Kame fused with Piccolo, later in Cell Saga Goku brought Dende on Earth who became the next guardian of the earth and made new dragon balls.
Aren't those two events or sets of events contradictory?