packager: problem with empty directories

I add the following lines in my qpg file:
<QPG:Add file=“buffer-L” type=“dir”
install="/machine/printers/" user=“root:root” permissions=“775”/>

when I execute packager it displays me a warning because buffer-L will
be created as an empty directory. What I know!

But when I install the package, buffer-L is not created!

If I use type=“tree” instead of type=“dir”, that works fine!

is it normal?