open(OUT,">>/home/public/SMDR/smdr$Year$month$day.pbx");
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This line could really use some kind of or die "Error: $!" clause on the end of it. You should always check the status of your opens (and sometimes even the closes). I would also check the fields you are writing to the file and using in the open statement. I also wonder about why you have the parse/write code in a different executable than the read code.

Update: tilly's right, fixed length formats are hard to get right (though it's hard to tell if that's even the problem here). That's why I sometimes like to use Parse::FixedLength and its debug option even though I generally might not use it when there are not that many fields (I would first try to figure out what your problem is though, or else you may end up with another problem -- figuring out another module).