Answer: Some clematis vines can take several years to become established and bloom well. Make sure your plant has reasonable fertility and moist soil (not soggy). The plants do best in rich, loose, fast draining soil, with the roots shaded and the tops in full sunshine. Your vine may not be getting enough sun if it's only 1/3 of the day. Your raised bed should actually promote good drainage, so I don't think that's the problem. You might want to apply a phosphorous source, such as bone meal, in spring. Phosphorous promotes blooming. Scratch it into the soil where the roots are actively growing and water well after applying.
You didn't mention what type you have, but the commonly grown Jackmanii hybrids are vigorous plants that flower on new wood, and flower best if the plant is severely pruned in the early spring, just as the buds begin to swell. I hope this info helps.
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