Artillery Bombardment ends turn early!

[cillmhor]

Just wondering if anyone has had this happen to them? I wanted to soften up a target hex with arty and get them out of entrenched. I had done so with artillery on several other turns in the current game without the turn ending prematurely before I could initiate the attack. However, to my surprise after two phases of bombardment, on the third phase, which should have left me with 70% of the turn, using the same arty pieces, the turn ended abruptly! I know that arty can fail cooperation etc and perhaps cause some problems for an attack, but I can't remember in my admittedly short TOW experience the turn ending after such a bombardment. Does anyone have any ideas?

Thanks in advance

Alasdair