Combobox Binding using WPF

Hello,

I have two combo boxes inside a grid view in two different columns. I need to bind the list of string to combo box. I can able to bind successfully to first combo box but when I try the same method for the second one it's empty. Please help me what can I try it out in this case, Am new to WPF with MVVM Architecture. 

<ComboBox x:Name="cmb1" Width="100" ItemsSource="{Binding list1}"><ComboBox x:Name="cmb2" Width="100" ItemsSource="{Binding list2}">

public List<string> list1 { get; set; }
public List<string> list2 { get; set; }

list1 = ConfigurationSettings.AppSettings["Data1"].ToString().Split(',').ToList<string>()

list2 = ConfigurationSettings.AppSettings["Data2"].ToString().Split(',').ToList<string>()