What is the name of your script?
Is it ./shutdown and works with the parameters root and 192.168.1.10 as the destination?
Maybe it´s helpful to post the complete script to have an better understanding.
Maybe you could post what the execution when started manually from the shell.
Rich wrote a Guide to help when having problems with the exec binding, maybe it´s worth a look?
It may be the future, but now in the present 
There are still many things that are only possible with files and not through PaperUI.