The mediators (MGM) use RTTI by default, so to get access to the TArticle properties, you must make them published (thus enabling RTTI access in your class).
public
constructor Create(const aID, aArticle, aCultivar, aKind, aSize : string); reintroduce;
published
property ID : string read FID write SetFID;
property Article : string read FArticle write SetArticle;
property Cultivar : string read FName write FName;
property Kind : string read FKind write SetKind;
property Size : string read FSize write SetSize;
All should then be fine - it works here. Tested under Win7 (64-bit).
ps: The tiOPF newsgroup server is back up and running. So if you could post future tiOPF questions there it would be much appreciated. Others could then benefit from questions and answers.