It's a group 2 which means it flowers in May and June on old wood, sespecially stems made the previous year. If dead headed after the initial flwoering and given a feed it will usually produce a smaller, second flush of flowers in late summer.
You will have to exercise patience till next spring but you may provoke it into flowering by gving it a generous dose of liquid tomato food and some special clematis food.
Next spring, cut out any dead wood and give it a good general purpose feed such as blood, fish and bone or pelleted chicken manure in Feb or March and then regular doses of clematis food to encoourage flower formation. All these fertilisers are available at good garden centres.