I don't understand perl at all but to me this looks way too complicated.
This challenge is solvable with an awk one-liner.
I really recommend a linux-based vm for many of the challenges here since tools like sed and awk really make it a lot easier.
see how you can (marginally modify and then) implement your approach in (g)awk and use that, if the source is correct it should work.
http://www.exploratorium.edu/pi/pi_archive/Pi10-6.html does work, I just did it again to check.