Two-way binding is only supported for properties exception.

That was very strange. I used #Bind in the markup of a user control in order to set a property value and got this nasty exception.

It told me nothing. I couldn't figure out what was wrong with the property and what does it mean that the property is not valid.

I did what every one of you will probably do ;)
Google with the exception and found that if you convert the property from the type it has to string it should work.

Couldn't make it.
Probably my scenario is different.
I will write another blogpost as soon as I find the solution. For now I worked it around another way - using the code behind ;)