Its not talking about the name of the file, but the package id you setup.
In your .xml files you have a <id></id> that contains your mods package identifier in the format of yourname:modname. It can't contain spaces. Choose this carefully as we rarely allow this to be changed. This identifier is used by SMF's package manager to uniquely identify a mod. Which lets you make upgrade mod packages for users among other things that it does.