The cause? a stray comma: print $fh, $sData instead of print $fh $sData.

I catch myself making the same mistake, and I've begun to habitually use the form print {$filehandle} $payload; to notify both me and Perl what I really mean. I'm amazed at how quickly "print" followed by curly braces feels like a new sigil; and it really decreases the amount of time I spend examining such statements for intent, not to mention examining them for errors.