Experts and BHG readers answer.
Climbing roses won't bloom
You do not say if your roses are the same variety or get about the same amout of sun. I wonder if the one that fails to bloom is close to the edge of the lawn? If so, I suspect it is getting extra nitrogen from the lawn fertilizer. Often if a rose is planted close to the edge of the lawn it will put on a lot of vegetaive growth caused by the extra nitrogen. This is at the expense of flowers. Try to counter the nitrogen with a phosphorus fertilizer to encourage flowers. Also I suggest bending the long stems down into an arc. This should force blooms along the length of the stem.