The specification for ADL rules has not been terribly reliable, although we retrospectively created a BASE release (1.0.4) that contained an older form of Expressions syntax and meta-model.
Nedap implemented this, and LinkEHR I believe implemented it (or close), but other tool support is patchy and probably not that reliable.
In any case, we are discussing how to specify rules in archetypes properly because it is more subtle than one might think on first look (including me, which is why I never got this part of the specification sorted out earlier 
If you can live without rules for a while longer I would suggest to do so, and wait till we crystallise a better form of the spec in the short term (feel free to make suggestions on the thread linked above).