Entity Framework 4.1 Code First Confused about lazy loading and Virtual

See more:

entity-framework

public class EntityDataProvider : DbContext, IDataProviderEntity
{
    public EntityDataProvider(string connectionStringName, bool enableLazyLoading = true)
            : base(connectionStringName)
        {
            Configuration.LazyLoadingEnabled = enableLazyLoading;
        }
}

POCO object Account:

public class Account
{
    ...
        private ICollection<CodeSegment> _codeSegments;
         public virtual ICollection<CodeSegment> CodeSegments
        {
            get
            {
                return _codeSegments ?? (_codeSegments = new Collection<CodeSegment>());
            }
            protected set
            {
                _codeSegments = value;
            }
        }
}

With the code above I get these results, which is what I expect
CodeSegmets.Count = 4

When I change the following:

Configuration.LazyLoadingEnabled = true;
public ICollection<CodeSegment> CodeSegments (removed virtual)

Results:
CodeSegments.Count = 0

Change:

Configuration.LazyLoadingEnabled = false;
public virtual ICollection<CodeSegment> CodeSegments (added virtual)

Results:
CodeSegments.Count = 0

Configuration.LazyLoadingEnabled = false;
public ICollection<CodeSegment> CodeSegments (removed virtual)

Results:
CodeSegments.Count = 0

Can anyone shed some light on this?