How to use valuation in sub nodes?

Hi all I have  complex structure like following:

businessobject MultipleLanguageOnTreeLevels {  [Label("Identification")] [AlternativeKey] element ID:ID;  [Label(" Name")]  element IdName:LANGUAGEINDEPENDENT_MEDIUM_Description;  [Transient] element CurrentLanguage : LanguageCode;  node Characterictics[1,n]{  [Label("Characterictis Name")] element CharactericticName:LANGUAGEINDEPENDENT_MEDIUM_Description;  node CharactericticDescriptions[0,n]{  [Label("Characteristics Language")]  element LanguageCode:LanguageCode;  [Label("Characterictis Description")]element Description:LANGUAGEINDEPENDENT_MEDIUM_Description;  }   association DescriptionInCurrentLanguage[0,1] to CharactericticDescriptions   valuation( LanguageCode ==  CurrentLanguage );  node Values[1,n]{  [Label("Value")] element Value:LANGUAGEINDEPENDENT_MEDIUM_Description;            node ValueDescriptions[0,n]{                 [Label("Value Language")]element    LanguageCode:LanguageCode;                 [Label("Value Description")]element Description:LANGUAGEINDEPENDENT_MEDIUM_Description;            }       }  }
}

I want to add association with valuation on second sub-node

association DescriptionInCurrentLanguage[0,1] to CharactericticDescriptions

  valuation( LanguageCode ==  CurrentLanguage ); but I receive syntax error that the element on Root - CurrentLanguage is not defined

is it possible at all to make such valuation if yes what is the right syntax to cite CurrentLanguage like root element in valuation.

Thank you in advance Ognian.