The code:

use foo qw/bar $baz/;
[download]

is the same as:

# Do this at compile time....
BEGIN {
  # load if needed
  require foo;
  # import functionality
  foo->import('bar', '$baz');
}
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Most errors (not this one, but most) where a require did not do what a use would are missing the import.

UPDATE
As merlyn points out, if your require does not match what you expected from use, and it wasn't a missing import, then likely you need the BEGIN block. Or else (as in this case) it is an unrelated mistake and the use wouldn't have worked either.