At first I thought you were pulling an April fool's joke Daniele but found out that you were not. ;)
Seems as though LunarDate ( ) only takes one parameter and SolarDate takes 2. although I am not quite sure if I can get them working properly yet.
I found that too...
Interesting, the localized version ( Italian ) has also those function localized.
But I haven't found a way to get some result from them.
May be that they belong to some Chinese functions.
EvaluationError ( LunarDate ( 1 ) )
returns 1223 - "The function referred to does not exist", so...
These functions have been there for a while - one can only assume they were planned but not implemented.
the new ( FMP11 ) HOL ( FileMaker Pro error codes ) says:
1223 "The function is not implemented"
It's actually been that way since v.8.5 at least (I need to update my calc file...). But it comes down to the same thing.