Option variables onX and osX are not passed to PayPal from my custom shopping cart

I created a custom shopping cart which allows visitors to add items to a shopping cart on my site and to checkout the items via PayPal.

PROBLEM: All the variables and their values are transfered to Paypal except on1,os1 and on2,os2 below.  

Your assistance in resolving this issue will be appreciated.

Thank you.



<form id="Paypal" name="Paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">
                  
<input type="hidden" name="cmd" value="_cart" />
<input type="hidden" name="upload" value="1" />
<input type="hidden" name="invoice" value="201177EF21FFAA5" />
<input type="hidden" name="shipping" value="11.2" />
<input type="hidden" name="item_name_1" value="Meade T-Shirt" />
<input type="hidden" name="amount_1" value="16.00" />
<input type="hidden" name="quantity_1" value="1" />
<input type="hidden" name="on1" value="Size" />
<input type="hidden" name="os1" value="Medium" />
<input type="hidden" name="shipping_1" value="11.2" />
<input type="hidden" name="item_name_2" value="Stylist's Cape" />
<input type="hidden" name="amount_2" value="24.99" />
<input type="hidden" name="quantity_2" value="3" />
<input type="hidden" name="on2" value="Color" />
<input type="hidden" name="os2" value="Lime Green" />
<input type="hidden" name="shipping_2" value="12.13" />
<input type="hidden" name="first_name" value="Peter" />
<input type="hidden" name="last_name" value="Jones" />
<input type="hidden" name="address1" value="200 Liberty Street" />
<input type="hidden" name="address2" value="" />
<input type="hidden" name="city" value="Liverpool" />
<input type="hidden" name="state" value="NY" />
<input type="hidden" name="zip" value="10010" />
<input type="hidden" name="email" value="peterj@noemail.net" />
<input type="hidden" name="business" value="shop@mydomain.com" />
<input type="hidden" name="no_note" value="0" />
<input type="hidden" name="currency_code" value="USD" />
<input type="hidden" name="lc" value="USA" />
<input type="hidden" name="return" value="http://www.mydomain.com/feedback-shop.aspx?PayPal=Success" />
<input type="hidden" name="notify_url" value="http://www.mydomain.com/feedback-shop.aspx" />
<input name="cpp_header_image" type="hidden" value="https://www.mydomain.com/images/ecomm/logoForPaypal.png" />
<input type="hidden" name="cancel_return" value="http://www.mydomain.com/feedback-shop.aspx?PayPal=Cancel" />
<input type="hidden" name="cn" value="How did you hear about us?" />
</form>