Buffy died in season 1, then at that moment Kendra was called.Buffy was revived by Xander, who performed CPR on her.In season 2, Kendra died.Faith was called.In season 5, Buffy died.No slayer was called because Buffy isn't the active slayer.Faith is.According to Joss, slayers are like batteries.Ounce it's been used, it's dead, and you can't use it again.A slayer wasn't called at Buffy's 2nd death, because she wasn't the active slayer.Faith is the active slayer.The slayer was not meant to be reborn.So she is not destined to call another.In season 7, the reason why Buffy said that a slayer will be called if she died, was because she wanted the potentials, who were goofing around, to be serious about it.At the same scene, Dawnie was there listening.Later, when Dawn thinks she's a SIT, she tells the gang, "If another slayer were to be called, then that'd mean SHE would have die, right?".SHE-Dawn didn't exactly say Buffy's name.The gang already knew Buffy couldn't activate another slayer.They though that Dawn meant Faith.I hope this answers everybodys question.
