I had the same error as following:
adb: ADB server didn't ACK
adb: * failed to start daemon *
ddms: 'C:\Users\samsung\AppData\Local\Android\sdk\platform-tools\adb.exe,start-server' failed -- run manually if necessary
So i followed the link to the adb.exe file and i run it manually, and it worked.
Also i killed the adb.exe from the task manager, and killed also another file that i can't recall its name but it ends with the word daemon.
Now both my lollipop and Kitkat versions are working probably. Hope that helpes
Note: for the phone with KitKat, i even did not install the USB driver, as it seems that windows 8.1 had figured it by him self.