q&a plugin gets 404 page

plugin install on wordpress multisite, running in one of the multisite subdomains.
for the example running on sub.domain.co.il
after installation of the plugin and saving permalink, the q&a plugin reach only 404 page. when i change the permalink to default it work. one more problem, when pressing author link (question) it reach this url http://www.domain.co.il/members/sagi/q-and-a/ but show nothing!! it send to the main domain and not the current site (sub domain).