How to obtain a list of objects inside another object using reflection

Using reflection I can obtain the object properties and values for all Data Types and the objects inside this object. But if the object contains a List of other objects I am having trouble in getting the objects in the list. The list can contain any type of object.

private static void SaveObj(object obj) {
   foreach (var prop in obj.GetType().GetProperties()) {
       if (prop.PropertyType.Namespace == "Entities") { //It is an object
           object obL = prop.GetValue(obj, null);
           SaveObj(obj);
       }
       else if (prop.PropertyType.Name == "List`1") { //This is a list of objects
           object obP = prop.GetValue(obj); 
           //obP has the list of objects, I can see the list in debug mode.
           List<object> obL = (List<object>)prop.GetValue(obj, null);
           //This line returns an exception!!
       }
       else {
           columns += prop.Name.ToLower() + ", ";
           values[i] = prop.GetValue(obj, null).ToString();
       }
       ... // the code continues ...
   }
}     

The exception message returned is: "It is not possible to convert an object of type 'System.Collections.Generic.List1[Entities.OrderItem]' to type 'System.Collections.Generic.List1[System.Object]'."

Interesting is that I can see all the objects and its contents in degug mode. In Immediate Window I can print the content of the variable obP with all the objects in the list, but how to read them?

Any ideas on how to solve this?