If you are using Acronis group server then you will have this problem.
Here is a possible solution:
1. First create a folder on your backup server and share it for everyone (just for now)
2. Setup a new task for your server.
3. In the backup location do not select Acronis Backup Server. Instead, browse to your backup server in my network places (username: domain\administrator account Password: Your password) and select the folder that you made in #1
4. Continue with the task setup until you come to your backup options.
5. Choose custom and make sure Archive Splitting is on automatic
6.Finish making the task.
Now run the task and you should now have an individual .TIB file located in the shared folder you made.
Hope that helped