ListView binding not working

I am getting errors while binding values in listview. I am using xamarin forms Xaml.

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This is the listview code. when I commented out the itemtemplate. it shows all the items from lstTimeZoneCities with value 'Models.Timezone'. So it means this is working and all i need is to set the itemtemplate. when I remove the comment code, i expect the listview is binded with actual values (city name) from lstTimeZoneCities. But it throws exception. I am not able to figure out the issue.

Could any one please have a look at it and let me know what the issue is?