[i3] Problems with some attributes in i3 bar config file

[Giuseppe Silletti]

Hi everyone! I'm new on i3 and I'm having some problems with some
attributes in i3 bar config file. For example the volume section doesn't
appear, even if I've put it in the config file. Also, some attributes like
status_chr of battery section make my bar having an error and not showing.
Can someone help me please?