Paypal integration issue on my custom cart

[neovantage]

Hi experts,
I am integrating paypal in my custom cart.

I am facing a issue in which it tells

"Your shopping cart is empty. Return to your merchant’s site to continue shopping."

Here is my code which i am using on my website page

<input type="hidden" name="business" value="neovan_1220700005_biz@gmail.com" />
<input type="hidden" name="cmd" value="_cart" /> 
<input type="hidden" name="upload" value="1" /> 
<input type="hidden" name="return" value="http://www.fs-clothing.com/checkout-success" />
 <input type="hidden" name="cancel_return" value="http://www.fs-clothing.com/checkout-error.php" />
<input type="hidden" name="rm" value="1" />
<input type="hidden" name="currency_code" id="currency_code" value="<?php if($_SESSION['cur']=="pkr"){ echo "PKR";}else if($_SESSION['cur']=="gbp"){ echo "GBP";}?>" />
 <input type="hidden" name="lc" value="GB" />
<input type="hidden" name="bn" value="toolkit-php" />
<input type="hidden" name="no_shipping" value="1" />

PHP Code

$str="";
$str=$str."invoice=".$invoice."&add=".$add."&business=".$business."&cmd=".$cmd."&return=".$return."&cancel_return=".$cancel_return."&rm=".$rm."&currency_code=".$currency_code."&lc=".$lc."&bn=".$bn."&no_shipping=".$no_shipping;

$itn=1;
for ($i=0; $i<$total_pro; $i++){
$str=$str."&item_name_$itn=".$prod_name[$i]."&amount_$itn=".$prod_price[$i]."&quantity_$itn=".$prod_quantity[$i];
				$itn=$itn+1;
			}
redirect("https://www.sandbox.paypal.com/cgi-bin/webscr".$str);

My string Output is

"
invoice=FSC-617-66669&add=&busi ness=neovan_122 0700005_biz@gma il.com&cmd=_car t&return=http ://www.fs-clothing.com/checkout-success&cancel_ return=http://www.fs-clothing.com/checkout-error.php&rm=1& currency_code=G BP&lc=GB&bn=too lkit-php&no_shipping =1&item_name_1= PRAWN STAR PINK&amount_1=6 .99&quantity_1= 1&item_name_2=K ILLER KA BHAI THRILLER&amount _2=6.29&quantit y_2=1
"

Can some one guide me where i am having an error and how can i fixed it. I will be really very grateful to you people.

Thanks in Advance

[neovantage]

I have solved my problem. I was passing parameters through get method due to which it was not upload my custom cart products on Paypal Cart. I used Post method and it is working fine now.

Thanks everyone