AUTHENTICATION OF USERS WITH ACTIVE DIRECTORY

hi Guys,

We have a fortigate 201E which we've setup to block social media access using a web filter profile with the policy granting access to the internet. However we've also created another policy to the internet with a web filter to allow social media access for specific users. The specific users are set as source in the policy. User authentication takes place with a domain controller on the network. The issue that we're dealing with is that some users that are allowed to access social media, at times are not able to do so. Checking the fortigate logs (user events) indicates that the user experiencing those issues doesn't appear to have signed in to the network (which is not true). Fortigate integration with the dc has been done without installing fsso agent on the dc. I would like some assistance or guide as to what the reason to this could be.