Capacitor toast not shown

I’m trying to use the capacitor toast plugin. no errors are occurring but the toast is never shown on the screen.
this is the code:

public async openToast(){
    const toast = await this.toastController.create({
      message : 'welcome',
      duration : 3500

any help? thanks

that’s not the Capacitor’s Toast plugin API, looks more like Ionic’s Toast.

this is Capacitor’s Toas API:

    text: 'welcome',
    duration: 'long'