Whats wrong with: IList> myIList = new List>();

Question

I am really confused about this List and IList things...and hope someone could help me out, THANKS!

My Question is about the second statement:

1. IList<int> myIList1 = new List<int>(); (O)

2. IList<IList<int>> myIList2 = new List<List<int>>(); (X)

3. IList<IList<int>> myIList3 = new List<IList<int>>(); (O)

I can understand that statement 1,3 works, but why statement 2 failed?