"Saving weka model [Solved]"

The Store operator is the way to go. You can use it with a combination of Retrieve and Apply Model in another process. If you still have problems please let us know and supply what exactly does not work.

Best regards,
Marius

I have found the problem and I think it is good that I report it.

I am working on a private data on a machine that cannot have access to the internet. I have installed RM but I cannot install the extensions, therefore, I have installed the extensions manually by copying the jar file into the plugins directory.
Storing and retrieving Weka models did not work.
Later, I have copied the extensions into the plugins/managed directory with the XMLfile and I was able to retrieve Weka models by the Retrieve component

Hm, that's strange. Which plugins directory did you use? To make it work you have to copy the extensions to C:\Program Files\Rapid-I\RapidMiner5\lib\plugins (i.e. in the installation directory, C:\Program Files\RapidMiner\RapidMiner5\lib\plugins for the latest version), not to the .RapidMiner5\plugins folder in your home directory. Did you do that?

Yes, first I used  "C:\Program Files\Rapid-I\RapidMiner5\lib\plugins"  but I had an error retrieving weka models.

It worked only when I copied the folder " C:\Program Files\Rapid-I\RapidMiner5\lib\plugins\managed" from another machine.

I have double checked.