Created Unassigned: Layout not correctly loading. [19988]

Hi guys, I having the following problem:

I'm saving my Layout like this:

var serializerSaver = new XmlLayoutSerializer(DockingManager);

using (var save = new StreamWriter(fileName))
serializerSaver.Serialize(save);

And loading it like this:

var serializerLoader = new XmlLayoutSerializer(DockingManager);

using (var load = new StreamReader(fileName))
serializerLoader.Deserialize(load);

Nothing strange so far.. But I wanna be able to close and open the docks I'm working with.
I'm re-opening them like this:

dockPanel3.AddToLayout(DockingManager, Xceed.Wpf.AvalonDock.Layout.AnchorableShowStrategy.Right);

The problem is .. if I load a saved Layout, the Event IsVisibleChanged stops happening. The Event is not triggered anymore ..
Does anyone know why? And how can I fix it?

Thanks