Unrecognized objects (Kangaroo)

Hey guys,
I am trying to use a definition on grasshopper. I have the latest version of Rhino, Grasshopper and Kangaroo. But It keeps giving me this message when i open the definition " There are five unrecognized objects in the file. Most unrecognized objects are part of a plug-in not installed on this machine. We've tried to harvest as much information as possible about this missing plug-in, but you will have to find and install it before this file will open correctly".
Does anyone know how to fix this ? 

Thanks in advance !