My Frage is simple, When Mr.Popo asked Shenron to bring back to life all those who were killed Von Frieza and his man, Why Nappa (Vegeta worked for Frieza when he killed Nappa) and all the Saiyan aren't resurrected?

well nappa and vegeta the didn't say they quit but it seemed like there stop working for frieza and they were going to earth to use the dragonballs to gain immortality and kill frieza so i don't think nappa was working for frieza anymore just didn't say he quit and the rest of the saiyans they got brought back in Weltraum and died because they can't breath in Weltraum poor saiyans.

I asked that Frage to myself before. I think I've figured it out.

When someone is resurrected, they go to the place they were killed. Planet Vegeta was destroyed alongside all the saiyans. So, they WOULD have been brought back, but they went to where Vegeta was, so they were floating in space, where they couldn't breathe, so they died again.

That's my theory.

Because they are evil bastard. Even without Frieza.

The soul's location in the afterlife, state of the soul, state of the body, time since death, number of times died, wording of the wish, and which set of Dragon Balls were used. All those items can interfere with a resurrection via dragon balls. His (and the other Saiyans) body was vaporized, so they would need an additional wish for his body. As that was a limitation of Earth's original Dragon Balls. The reconstituted bodies of the Saiyan people would need to be moved as well.