Programming for commerce.cgi shopping cart-Shipping by category

Please don't tell me to go to Commerce.cgi, I have been there and got no help.
I am not even sure I have the right
I get this error in the checkout:

Software error:
Undefined subroutine &main::shipping_by_category called at
./library/shipping_lib.pl line 44.

Here is the script I rewrote and changed from the one in commerce.cgi This
script works anyway the first part does if I change the name of the script to
"shipping_by_subtotal.pl" and change the "sub shipping_by_category" to
shipping_by_subtotal"
But when I order by a different category it still uses the same shipping
price.
I guess I might be leaving something out. I am not too sure if the
category_count is the correct way of picking the category to be used. I hope
you can understand what I am writing. Or have any suggestion, maybe I am way
off base. I place this script in the add-on folder

sub shipping_by_category
{
local ($shipMethod, $subtotal, $weight, $total_shipping, $category_count) =
@_; local ($shipping_price);

if ($category_count{'Gifts_Novelty'} eq "") {

    if ($subtotal <= 100.00)      { $shipping_price = 5.95;  }

      elsif ($subtotal >= 101.00 && $subtotal <= 249.00)   { $shipping_price =
7.95;  }
      elsif ($subtotal >= 250.00 && $subtotal <= 499.00)   { $shipping_price =
9.95; }
     
      # All orders over the previous value
      else { $shipping_price = 0.00; }
   

} else {

if ($subtotal <= 20.00)      { $shipping_price = 7.00;  }

      elsif ($subtotal >= 30.00 && $subtotal <= 39.00)   { $shipping_price =
8.50;  }
      elsif ($subtotal >= 40.00 && $subtotal <= 49.00)   { $shipping_price =
10.00; }
      elsif ($subtotal >= 50.00 && $subtotal <= 59.00)   { $shipping_price =
11.50; }
      elsif ($subtotal >= 60.00 && $subtotal <= 69.00)   { $shipping_price =
13.00; }
      elsif ($subtotal >= 70.00 && $subtotal <= 79.00)   { $shipping_price =
15.00; }
      elsif ($subtotal >= 80.00 && $subtotal <= 89.00)   { $shipping_price =
19.00; }
      elsif ($subtotal >= 90.00 && $subtotal <= 99.00)   { $shipping_price =
23.00; }
      elsif ($subtotal >= 100.00 && $subtotal <= 119.00)  { $shipping_price =
27.00; }
      elsif ($subtotal >= 120.00 && $subtotal <= 129.00)  { $shipping_price =
32.00; }

      # All orders over the previous value
      else { $shipping_price = 38.00; }
   }
   return ($shipping_price);
}

1;