Lambda expression used inside Include is not valid. EF6, Navigation Property

Question

I was trying to solve a many to many relation. On a database level everthing looks good to me, but when I tryr to get that data(inlcude), it fails.

I get:

Lambda expression used inside Include is not valid.

What I call/tried:

var readRecipes = db.MyClasses. 
                     Include(blog => blog.SomeCollections).ThenInclude(post => post.Prop1).
                     Include(blog => blog.SomeCollections).ThenInclude(post => post.Prop2).

Structure

MainClass:

public class MainClass{
// ...                   
public ICollection<NavigationProperty> NavigationPropertys; 
// ...               
public MainClass()
{

    this.NavigationPropertys = new Collection<NavigationProperty>(); 
}
}

NavigationProperty:

public class NavigationProperty
    {
        public Guid ID { get; set; }



        [Required]
        public Guid? Prop1ID { get; set; }// 0,*

        [Required]
        public Guid? Prop2ID { get; set; }// 0,*

        [Required]
        public Guid MainClassID { get; set; }



        [Required]
        public Prop1 Prop1 { get; set; }

        [Required]
        public Prop2 Prop2 { get; set; }




        public MainClass MainClass { get; set; }



        [Required]
        public float Amount { get; set; }


        public NavigationProperty()
        {
            // todo: ?
        }
    }

I don't know, what I did wrong ?

Answer 1

Ok, I solved my question.

Instead of:

public ICollection<NavigationProperty> NavigationPropertys; 

I should have used:

public ICollection<NavigationProperty> NavigationPropertys { get; set; }; 

This made Lambda crash.

Thank You.