is rightnavbar button only for push n pop for iphone

Question

i am calling a alert view in rightnavbarbutton then inside that if buttonindex==0 then i am doing this

[self.navigationController popToRootViewControllerAnimated:YES];

but my app just quit after that and when i pass dirctly without alert button then its fine

so is it true that i cant write alertbutton code in navrightbutton????