In the main loop

        die qq{no sids found\n} unless @sids;
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does what is says on the tin. :-)

Perhaps replace that line with something like

if (not @sids){
  print qq{no sids found in $cpid\n};
  next;
}
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That way it will print a message and simply move on if none are found.

On a side note you could declare

    my $url = q{http://csr.wwiionline.com......etc.};
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before the main loop as it is the same everytime.

Also,

my $pidlist = <$settings>;

# Get list of pids and process all
while ( $pidlist = <$settings> ) {
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is reading a line from the file and then throwing it away. It is starting on the second line of the file. Remove the first declaration and change the while to

while (my $pidlist = <$settings>){
  #...
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I reckon it's shaping up nicely. :-)