My Jasminum officinale is two years old and 2.4 m (8ft) tall and it hasn't flowered.

Could you give me any possible causes of this?

Jasminum officinale needs a hot, sunny, situation to flower well.

If it is not planted in such a situation, move it this autumn and replant it in a more suitable spot.

Cut back the stems by about half their length and lift the plant with a good ball of roots attached.