ShellScript return <empty string> in Zabbix

[rafael.queiroga]

I created a .sh file on Macos that returns the Maximum Capacity of the battery. On MacOS I return the correct value of the percentage I still have battery, however in the Item that I created in Zabbix passing the parameter from the same shell script, it returns as <empty string>.

What can I do to correct it and make the percentage appear?