This is a common problem for Dreamweaver users. Here is the problem:
When people try to synchronize in the Site Manager, an error pops up that says that Dreamweaver is unable to determine the remote server time, so synchronization is not possible.
Here is the reason:
In order to determine the server time, instead of checking the clock (which would make sense to me!) DW tries to create a temporary directory, checks the time at which that directory was created, then removes that directory. It takes this time/date and compares it to the time/dates of the files you want to synchronize, and transfers newer files, etc.
Here is the solution:
The person doing the synchronization needs to have write access to the directory that they are transferring files into. (The path that is listed in their Remote Path box.) That way Dreamweaver is able to create the necessary temporary directory and check its time. This can be in the form of a group definition (giving that particular group write access) or by changing the owner of the file to that particular user. (Caution: If multiple people are transferring files to the same location, make sure that they can all still access what they need to!)