Next Page not shown sometine

this.navCtrl.setRoot(SecondPage, {
        x: 1

I have used this for navigating to another page. But some time I successfully able to move to SecondPage and sometime not.

why use setRoot to navigate
use this.navCtrl.push(SecondPage,{x:1});

I already done that. But when I use nav.push then sometime my previous models are shown into some random pages.(means there view part in shown into some other page that’s why I use serRoot for navigation).