the read request flag (<) should be just before the GA
Type number : statutModeChauffageChambre5 "Statut Mode chauffage chambre 5" [ga="5.001:<4/3/1"]
see examples here: KNX1 to KNX2 Migration Steps
Also: it is advisable to use a different name for the Channel and the Item. It’s not a problem… it’s just easier to identify them