I have a couple of questions. 1) Before you planted, did the rhizome show signs of life such as a sprouting node? 2) Did you plant it deeper than an 1"?
I planted about 20 rhizomes way back in April from my LHBS and from Homercidal and all came up within a week and some in 3 or 4 days and this was a month ago. I plant them horozontal with a light covering of soil and I make sure there is at least a couple of sprouts starting. I think these are very easy plants to grow so if you follow this, you should be ok. If you think maybe you planted them too deep, carefully dig them up and reset them.
The soil temps. are plenty high enough so that would not be a factor.