So, it wasn't dead?!
I planted a "Barb. Jackman" 4 years ago, and in that time it flowered once and only came up twice. I have literally a dozen or more clematis scattered throughout the property, so I am no novice. There are a few more clematis and roses along that fence, so I decided to dig up the problem clemais and plant an Austin climbing rose (Gertrude Jekyll) - we'll see how that performs.
Anyway, I started digging up the "dead" clematis and the root ball was not only very much alive (no above ground shoots), but it was the size of a bowling ball! Instead of throwing it away, I decided to move my apparently part-time clematis to a less conspicous place in the corner of the yard in case it ever comes up again.
There is a Nelly Moser planted at the end of the yard under an arch and it too, never comes up faithfully, while its twin sister (purchased at the same time, and planted at the same time) on the other side of the arch, is already half-way up.
Clematis are trully plants requiring patience!