FSSO in 5.2 problem

Hi, on Fortigate 100D ver 4.x we used a FSSO with FSSO Agent installed on Active Directory server with no trouble. After change firmware to 5.2 and FSSO Agent to 4.3.0159, users started complain about websites: sometimes websites opened and sometimes not. I decided to change SSO method to Polling. I configured everything with no luck. no users are shown in User & Device -> Monitor -> Firewall -> Show all FSSO Logons. The " diagnose debug authd fsso server-status" command shows only " Local FSSO Agent" !! which is not visible under User & Device -> Single Sign-On (I even deleted everything I created before): LDAP test: pass. When I add a SSO, the status is always grey X mark.