Please provide a complete example. Put your parsing code back with your reading code, because your just creating more places for your program to go wrong. Check the status of your open as I said before. Provide some sample input and put it in a DATA section, like the following (the following is pseudo code, please fill in with actual code):

while (<DATA>) {
  #parse data
  #open output file
  #write data to output file
}
# close output file

__DATA__
#some sample input
[download]

Once you turn the above into real code, if you are still having problems with it, then ask again. If you get the above working, then replace a bit at a time (e.g. open your real input source -- maybe it's the problem, and I don't know why you're using sysopen instead of open) until you get your desired result.