using "file" with a nonspecific name

function bla
pop $0
file $0
functionend

there's more to it than this, but it doesn't like this..

Pop: $0
File: "$0" -> no files found.
Usage: File [/nonfatal] [/a] ([/r] filespec [...]|/oname=outfile one_file_only)
Error in script "Install.nsi" on line 259 -- aborting creation process

reading about the switches, i don't see anything that will help me out..

ideas?