In Lansweeper i have been comparing what it has discovered in AD versus what is actually there. we have on OU in AD that has 91 objects User's in this case. In Lansweeper it is only showing 11 of the 91 listed in that OU.
Please note that Lansweeper currently only adds AD users to your database if they are found logged onto a computer during a scan.
In Lansweeper 5.0, which is currently in development, there will be an option to import any and all AD users. We expect to have a 5.0 beta release ready by October.