Phylli, generally speaking type III clematis do not respond to propagation via any means other than layering and cuttings. Propagation by seed is not a good means since the clematis in question is a hybrid and will not come true from seed. If you do try propagation from seed again, then just realize that what you get from it may or may not resemble the parent plant and that germination of the seeds can possibly take up to a year. If you want to try layering, then try trimming a stem down in early spring and catch it as it puts out new growth and prior to its getting attached to the chicken wire. Then you can layer it into the soil or even a pot of potting mix.