Automatic properties and Nullable types - are they incompatible?

Question

I have a custom type with a nullable property that I am trying to project into from a nullable column in SQL. I am always getting a 'missingmethodexception' like so:

{"Method not found: 'Void MyType.set_Number(System.Nullable`1<Int32>)'."}

Is there a problem with trying to project into a custom type with nullable automatic properties? The code looks like this:

public class MyType {        
    public string Name {get;set;}
    public decimal Value { get; set;}
    public int? Number { get; set;}
}

Dictionary<int, CustomType> dict;

dict = (from t in table
        select new {
           id = av.Account.Id,
           mt = new MyType { Name = t.Name, Value = t.Value, Number = t.Number }
        }).ToDictionary(item => item.id, item => item.mt);