Make these changes and see if it provides any clues:

#!/usr/bin/perl

print "Attempting shutdown script\n";
my $sysret = system("./server_down.sh");
print "-----[ Results ]---------------\n";
print "$sysret\n";
print "-----[ End of Results ]--------\n";


#script terminates here, why ????
#below lines will not execute
print "line 1";
print "line 2";
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If nothing prints after "Attempting ...", then you have a problem with the shell script (or at least your efforts to invoke it).