Hi Yvonne.  Thanks for contacting the Extension Master Gardener Helpline.
It always takes a bit for newly planted Clematis vines to settle in.  There are a couple of things you can do to ensure success, though.
First, ensure it has fertile, loamy, well-draining soil.  Good quality compost is better than a chemical fertilizer for making sure they have plenty of nutrition.  Simply put an inch or two around where it's planted, and water it in well.  Make sure to pull the compost away from the stem, though.
Second, make sure that the vine itself is in sunshine but the roots are in shade.  You can do this by planting it under other shrubs or putting a stone over the root zone.
The following description may also be helpful:
”Head in the sun, feet in the shade” –
that’s the old adage for success with clematis. They thrive when the vine itself gets plenty of sunshine, while the base of the plant and roots enjoy cool, shady conditions. You can accomplish this with mulch, by planting it where the root zone is sheltered by a neighboring shrub, or with some slate or rocks, which mimics how clematis grow in nature.
This group blooms later and from new growth. These should be pruned in February or March as new leaf buds begin to show low on the plant. Also remove all dead material above the buds and clean out any old or mildewed foliage at this time.
I hope this helps.  Good luck!
Jessie, Extension Master Gardener Helpline Volunteer

Thank you for the advice; I have done that.