The Navisworks Timeliner script can work with multiple Navisworks versions. at the moment NW Manage and Simulate, 2016, 2015 and 2014 are supported. However, you have to tell the script which version it should work with. It can only work with one NW version at a time. The script will indicate which versions you have installed, but this is not 100% solid.
You can tell the script which NW version should be used by going to the options rollout.
Pick the NW version you want to use.
You can also re-install the NW plugin through the menu of the 3ds Max script. Use the menu > Navisworks > Install navisworks plugin... To see if it worked you can check the log-message in the log-rollout of the script and you can also check if the file has actually been placed in the right location. The plugin file should be installed here: C:\Users\[USERNAME]\AppData\Roaming\Autodesk Navisworks [VERSION]\Plugins\Timeliner_plugin.KLAAS\Timeliner_plugin.KLAAS.dl.
Use the menu to reinstall the NW plugin
Check the log to see how the installation went