Paypal Internal Server Error - Read when posting values from mobile browser

I am using below script to post all my values to paypal.

If I send it from my desktop computer it works.

If I use my mobile browser I will receive the following

error message:

Internal Server Error - Read The server encountered an internal error or misconfiguration and was unable to complete your request.

Reference #3.62b454b8.1429451178.1d8b6819

<!-- Start Paypal form-->

<form name="paypal" [link removed] method="post">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="upload" value="1">
<input type="hidden" name="business" value="info@nextlevelgarments.com">
<?=$ppal;?>
<? if($pshipping!="0"){ ?> 
<input type="hidden" name="handling_cart" value="<?=$pshipping;?>">
<? } ?>
<!--add items
<input type="hidden" name="item_name_1" value="Item Name 1">
<input type="hidden" name="amount_1" value="1.00">
end add items


-->
<div style='width:100%; height:80px; margin-top:30px; padding:2%;         border:#CCC 1px solid;' class="elembg1 curved4">
<h4>Shipping: <?=$pshipping;?> <?=currout($curr);?></h4>

<h3>Grandtotal: <?=$pgrandtotal;?> <?=currout($curr);?></h3>
</div>
<br />
<br />


<input type="hidden" name="currency_code" value="<?=$curr;?>">

<input 
type = "hidden" 
name = "return" 
value = [link removed]<?=$purchaseid;?>&email=<?=$email;?>&name=<?=$wname;?>"
>
[image removed]<br />
<br />
<br />

<input class="button_right" type="submit" value="Pay here">
</form>


<!--End Paypal Form-->