VisitsSummary.get missing Unique Visits

I have installed and configured piwik on our server . When I use the api VisitsSummary.get it is missing nb_uniq_visitors . Is there something I need to configure more?


<result>
<nb_visits>2</nb_visits>
<nb_actions>8</nb_actions>
<nb_visits_converted>0</nb_visits_converted>
<bounce_count>0</bounce_count>
<sum_visit_length>2363</sum_visit_length>
<max_actions>5</max_actions>
<bounce_rate>0%</bounce_rate>
<nb_actions_per_visit>4</nb_actions_per_visit>
<avg_time_on_site>1182</avg_time_on_site>
</result>

In the demo it is showing


<result>
<nb_uniq_visitors>1431</nb_uniq_visitors>
<nb_visits>1699</nb_visits>
<nb_actions>5346</nb_actions>
<nb_visits_converted>74</nb_visits_converted>
<bounce_count>1030</bounce_count>
<sum_visit_length>410226</sum_visit_length>
<max_actions>98</max_actions>
<bounce_rate>61%</bounce_rate>
<nb_actions_per_visit>3.1</nb_actions_per_visit>
<avg_time_on_site>241</avg_time_on_site>
</result>