mnt Permission Issue (newbie)

I ran into a permissions problem. I am using writelines code to create a file in File.DirRootExternal that works perfectly.

I can see the file but when I try to access it on a startup line through Busybox I get Permission Denied.

Do I need to change permissions on the mnt folder and can I do that.
The permission for mnt currently shows drwxrwxr-x

Thanks to everyone for their help.