Assigning Object() containing reflected class MyItem objects to reflected class property MyItems()

I've run into an issue where I need to load a class into my code using reflection, create an array of that class, and then assign the array to another reflected object's property.

My minimum example would be:

My DLL:

Public Class MyItem
    Public Property Id As Int32
End Class

Public Class MyMainItem
    Public Property MyItems As MyItem()
End Class

My Test App:

Sub Main()
    Dim myAssembly As Assembly = Assembly.LoadFile("c:\temp\MyDll.dll")
    Dim myMainObject As Object = Activator.CreateInstance(myAssembly.GetType("MyDll.MyMainItem"))
    Dim myItemArray(1) As Object

    myItemArray(0) = Activator.CreateInstance(myAssembly.GetType("MyDll.MyItem"))
    myItemArray(1) = Activator.CreateInstance(myAssembly.GetType("MyDll.MyItem"))

    myMainObject.MyItems = myItemArray
End Sub

The error I receive is InvalidCastException when assigning myItemArray to MyItems:

Conversion from type 'Object()' to type 'MyItem()' is not valid.

Is there a way to make myItemArray be understood as an array of MyItem rather than Object?