Flex 4: Replace one mxml instance with another destroys the bindings

Flex 4: Replace one mxml instance with another destroys the bindings

I want to replace on mxml instance with another. The instance I try to
replace is a custom component that has an object that I bind, component
that also has a skin that has a property I bind.
The issue I experience takes place when I replace the mxml instance with
another. All the properties I bind are still working in the custom
component but the property I bind in the custom component for the skin is
not working anymore.
This is the way I bind the custom skin property in the skin file:
<fx:Binding source="hostComponent.lineAlpha" destination="lineAlpha" />
What causes this to stop listening and what can I do to fix that?