Spells: "Spell did not take hold" when healing

[Clinicus]

I've only had this happen a couple of times, but as a healer it's pretty scary so I thought I better report it.

It's happened twice that I can remember, both times with the Lesser Healing spell. Once I was duoing with a warrior, another time was with a full group. It casts, and consumes mana, but gives me a spell did not take hold message, and does not heal the target. Both times it only happened for one encounter. Once the mob was dead, the problem went away.

Let me know if there are any more specifics you need. I played a cleric for years on live and I don't remember having this problem before.