This is often an indication that Zookeeper wasn't properly installed and therefore not loaded by 3d Studio Max.

Please make sure that you have the following files installed:

1. 3DSMAX_ROOT\Autodesk.Max.dll
2. 3DSMAX_ROOT\Plugins\Autodesk.Max.Wrappers.dlu
3. 3DSMAX_ROOT\Plugins\Ephere.Plugins.Autodesk.Max.Zookeeper.dll

3DSMAX_ROOT is the folder where your 3d Studio Max is installed. Note that if you have installed Zookeeper in a location other than "\Plugins" change that accordingly. If any of the files listed above are not present please run the web installer to reinstall Zookeeper. It will update the needed files.

If you still have trouble after reinstalling Zookeeper please let us know.