If you look closely at $sysKey, you'll see that it never gets set to anything. I think you wanted something like this... (tested, would you believe!)

[first 3 lines as per your code]

my $sysKey = $Registry->{"LMachine/SYSTEM/CurrentControlSet/Control/Pr
+int/Printers/"}  ;
my @Print_Printer = grep( m#^/#, keys %$sysKey);

[last 3 lines as per your code]
[download]

As to the grep/regex, it only 'lets through' keys that start with '/'. The keys of $sysKey start off as (on my machine) as... CAPTURE FAX BVRP/, Capture fax BVRP Extended/, Speedway!fax/, Brother HL-1250 series/, /, /StartOnBoot,/PrintersMask/ after the grep, we're left with...

/StartOnBoot
/PrintersMask
[download]

...which is presumably what you were looking for.

HTH, Ben.