I had the same issue and set mine like this. The result is pretty much the same as Sic's. Not sure if doing it this way makes much of a difference, but I think it will avoid unnecessary attempts to click the rod when it's not ready.
Code:
Buffs15=command: /useitem Sickle of Umbral Modulation|Mana|75|Cond1
Cond1=${Me.ItemReady[Sickle of Umbral Modulation]}