ListView within a ListView doesn't bind

<Window.Resources><local:FixedNumberCountConverter x:Key="Converter"/><DataTemplate x:Key="StepList"><StackPanel Orientation="Horizontal"><TextBlock Text="{Binding J}"></TextBlock><TextBlock Text="{Binding StartValue}"/><TextBlock Text="{Binding D}"/><TextBlock Text="{Binding Lambda}"/><TextBlock Text="{Binding NewValue}"/></StackPanel></DataTemplate><DataTemplate x:Key="IterList"><StackPanel Orientation="Horizontal"><TextBlock Text="{Binding I}"></TextBlock><TextBlock Text="{Binding Value}"></TextBlock><ListView ItemsSource="{Binding Step}" ItemTemplate="{StaticResource StepList}"/></StackPanel></DataTemplate></Window.Resources>
...<ListView Name="ResultDetails" MaxHeight="360" Grid.Column="3" FontSize="12" ItemTemplate="{StaticResource IterList}"></ListView>

class is like this:

using System;
using Model;

namespace View
{
    class Temp
    {
        public Temp(int i, string value, int j, string startValue, Vector d, double lambda, string newValue)
        {
            I = i;
            Value = value;
            Step = new Tuple<int, string, Vector, double, string>(j, startValue, d, lambda, newValue);
        }

        public int I { get; private set; }
        public string Value { get; private set; }
        public Tuple<int, string, Vector, double, string> Step { get; private set; }
    }
}