Property does not return value from private field
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I'm facing a strange behaviour of one of my properties in my MonoTouch-Application. 
It seems that the given value can not be returned by the Property, but the Debugger in MonoDevelop says that the private field in the background actually holds the value??

Here you can see how the property got implemented:
http://imageshack.us/photo/my-images/213/propertyimplementation.png/

And here you can see what the Debugger says:
http://img818.imageshack.us/img818/2226/propertyw.png

How is it possible that the reflected value ("value") holds the correct value, and the reflected field "has_value" says that it's not holding any value at once? For this reason it's not possible to get the value from the property.

(The only difference between this and my other properties is that this property is nullable)