Snapshot Backup solution needed

I have been testing different backup solutions and non seem to work for what I need it to do. I need a backup solution that will work similar to Time Machine in a sense that it will create snapshots everyday and that the users can just select a date for when they remember a file working, and can go back to that version of that file. But my problem is that I don't want it backing up to external hdds or a separate volume on that computer. I need it to backup across the network to a windows file share. There are programs out there that will not backup across a network, and the ones that can, do not provide the snapshot function that I need. Bootable volumes would be great, but that isn't necessary. I just need it to work with the environment that we are currently in. Time machine seems to lock up the files that my users are using, and if they don't save before the time machine backup, it will get rid of all the work they had done. Any thoughts?