ms project london - Resource allocation

I have a resource, SH, who is available to me for 40% of a 35 hour week. I need him to do a task that will take 2 days ie. 14 hours. This should mean that the task will take 1 week elapsed time to complete. I have set the task to Fixed Work, the resource availability to 40%, and the task duration to 2ed. But still seem to be showing a task duration of 2 days on the Gantt chart. So - I'm missing something somewhere!
Regards,
Karen