Change the number of results per page

I want to display the result with only 10 members per page. By default, all results is display in the same page.

I have find the parameter $params[‘per_page’] and set it to 10 but the result show only the 10 first result. There is no next button…

How I can do to display 10 members with button ?

Thanks

http://wordpress.org/extend/plugins/bp-profile-search/