$allmondayflag = 1;
        
    foreach my $orderfile (<$instance_root/order_temp/ord.*>) 
    {
            print "\nProcessing Order File: $orderfile\n";
                
        open (FILEH, $orderfile) or die "Could not open order file: $o
+rderfile : $!";
        
              while (my $line = <FILEH>)  # loop as long as there are 
+records in the file
              {
                   my $ordertype = substr($line, 0, 2);  # used to fin
+d the order header

                   if ($ordertype eq "HM")  # only look at the dates o
+n the header records
                   {
                    my $ordernum = substr($line, 2, 7);
                     my $date_str = substr($line, 64, 8);
                            my ($year, $month, $day) = $date_str =~ m/
+(\d{4})(\d{2})(\d{2})/;
                      my $time = timelocal("", "", "", $day, $month-1,
+ $year);  # For $month:  Jan = 0, Feb = 1, etc.

                      if ((localtime($time))[6] == 1 )  # the order is
+ on a Monday
                      {
                      print "  Order Number =  $ordernum   Order Date 
+= $date_str is a Monday\n";
                          $allmondayflag = 1;                
                      next;  # move onto the next record in the curren
+t file
                      } 
                      else 
                      {
                            # We have found an order date that is not 
+a Monday
                            $allmondayflag = 0;
                        close FILEH;
                        last;  # bail out of the loop if date is not M
+onday and process the next order
                      }    
                }  # end of Ordertype IF
                }  # end of while loop
                
                # Decide where to move the file based on the allMonday
+Flag
                if ($allmondayflag) 
          {
                 print "  Order Number =  $ordernum has order dates th
+at are all Mondays. This is a bad order file and is being moved to $b
+adordpath\n";
                   move("$orderfile", $badordpath) or die "\nCould not
+ move the file $orderfile. Move failed: $!";
          } 
          else 
          {
               print "  Order Number =  $ordernum   Order Date = $date
+_str is not a Monday.\n";
               print "  This file is valid and is being moved to $good
+ordpath\n";
               move("$orderfile", $goodordpath) or die "Could not move
+ the file $orderfile. Move failed: $!";
          }
          
                close FILEH;  # close file when we run out of lines to
+ read
        }  # end of ForEach loop
} 
else 
{
    my $where = "$instance_root/order_temp";
    print "Directory $where does not exist...now exiting\n\n";
}
[download]

That's because you defined $ordernum in this block:

if ($ordertype eq "HM")
[download]

But then tried to use that variable outside of the block. You need to change the scope of the variable since the movement code block was relocated.