You do not have the necessary read, write and append privileges on the selected network backup disk

I have OSX Server running on a mac mini in my home. I've been using it for doing Time Machine backups from my MacBook. This worked fine until I changed the password for my user account on the mac mini. At that point, backups on my laptop started failing, indicating that I needed to update the password that the laptop was storing for the mac mini. However, when I try to do so (at **System Preferences > Time Machine > Select Backup Disk...**), I get the following error: > "You do not have the necessary read, write and append privileges on the > selected network backup disk." The laptop is running OSX 10.9, and the mac mini is running OSX 10.8. Has anyone using OSX Server for backups experienced something similar to this? Does anyone know how to fix it (without losing all of my previous backups)?