Hi there, i follow a tutorial from www.phpwebcommerce.com and i'm having path problem for 'add to cart' button.

Demo from phpwebcommerce: http://www.phpwebcommerce.com/plaincart/index.php
I have modified some changes, i'm putting the 'add to cart' button to 1st level instead of 2nd level. Example, under all category (car & manga) i choose car, then inside car category list there is a 'add to cart' button under all car product instead of clicking inside and show 'add to cart' button.

productDetail.php:
PHP Code:
<?php
if (!defined('WEB_ROOT')) {
    exit;
}

$product getProductDetail($pdId$catId);

// we have $pd_name, $pd_price, $pd_description, $pd_image, $cart_url
extract($product);
?> 
<table width="100%" border="0" cellspacing="0" cellpadding="10">
 <tr> 
  <td align="center"><img src="<?php echo $pd_image?>" border="0" alt="<?php echo $pd_name?>" width="230" height="170"></td>
  <td valign="middle">
<strong><?php echo $pd_name?></strong><br>
Price : <?php echo displayAmount($pd_price); ?><br>
<?php
// if we still have this product in stock
// show the 'Add to cart' button
if ($pd_qty 0) {
?>
<input type="button" name="btnAddToCart" value="Add To Cart &gt;" onClick="window.location.href='<?php echo $cart_url?>';" class="addToCartButton">
<?php
} else {
    echo 
'Out Of Stock';
}
?>
  </td>
 </tr>
 <tr align="left"> 
  <td colspan="2"><?php echo $pd_description?></td>
 </tr>
</table>
I copy this code out from productDetail.php:
Code:
<input type="button" name="btnAddToCart" value="Add To Cart &gt;" onClick="window.location.href='<?php echo $cart_url; ?>';">
productList.php:
PHP Code:
<?php
if (!defined('WEB_ROOT')) {
    exit;
}

$productsPerRow 2;
$productsPerPage 8;

//$productList    = getProductList($catId);
$children array_merge(array($catId), getChildCategories(NULL$catId));
$children ' (' implode(', '$children) . ')';

$sql "SELECT pd_id, pd_name, pd_price, pd_thumbnail, pd_qty, c.cat_id
        FROM tbl_product pd, tbl_category c
        WHERE pd.cat_id = c.cat_id AND pd.cat_id IN $children 
        ORDER BY pd_name"
;
$result     dbQuery(getPagingQuery($sql$productsPerPage));
$pagingLink getPagingLink($sql$productsPerPage"c=$catId");
$numProduct dbNumRows($result);

// the product images are arranged in a table. to make sure
// each image gets equal space set the cell width here
$columnWidth = (int)(100 $productsPerRow);
?>
<table width="100%" border="0" cellspacing="0" cellpadding="20">

<?php 
if ($numProduct ) {

    
$i 0;
    while (
$row dbFetchAssoc($result)) {
    
        
extract($row);
        if (
$pd_thumbnail) {
            
$pd_thumbnail WEB_ROOT 'images/product/' $pd_thumbnail;
        } else {
            
$pd_thumbnail WEB_ROOT 'images/no-image-small.png';
        }
    
        if (
$i $productsPerRow == 0) {
            echo 
'<tr>';
        }

        
// format how we display the price
        
$pd_price displayAmount($pd_price);
        
        echo 
"<td width=\"$columnWidth%\" align=\"center\"><a href=\"" $_SERVER['PHP_SELF'] . "?c=$catId&p=$pd_id" "\"><img src=\"$pd_thumbnail\" border=\"0\" width=\"230\" height=\"170\"><br>$pd_name</a><br>Price : $pd_price<br>
        <input type=\"button\" name=\"btnAddToCart\" value=\"Add To Cart &gt;\" onClick=\"window.location.href='<?php echo $cart_url; ?>';\" >"
;
        
        

        
// if the product is no longer in stock, tell the customer
        
if ($pd_qty <= 0) {
            echo 
"<br>Out Of Stock";
        }
        
        echo 
"</td>\r\n";
    
        if (
$i $productsPerRow == $productsPerRow 1) {
            echo 
'</tr>';
        }
        
        
$i += 1;
    }
    
    if (
$i $productsPerRow 0) {
        echo 
'<td colspan="' . ($productsPerRow - ($i $productsPerRow)) . '">&nbsp;</td>';
    }
    
} else {
?>
    <tr><td width="100%" align="center" valign="center">No products in this category</td></tr>
<?php    
}    
?>
</table>
<p align="center"><?php echo $pagingLink?></p>
The code i copy from productDetail.php i paste in productList.php at line48, it show the 'add to cart' button but when i click on it, it cant add to my shopping cart and it show error:

Notice: Undefined variable: cart_url in C:\Domains\xxxxxxxx\wwwroot\xxxxxxxx\plaincart\include\productList.php on line 48
Notice: Undefined variable: cart_url in C:\Domains\xxxxxxxx\wwwroot\xxxxxxxx\plaincart\include\productList.php on line 48
Notice: Undefined variable: cart_url in C:\Domains\xxxxxxxx\wwwroot\xxxxxxxx\plaincart\include\productList.php on line 48
Notice: Undefined variable: cart_url in C:\Domains\xxxxxxxx\wwwroot\xxxxxxxx\plaincart\include\productList.php on line 48

Will Appreciate For Any Help....Thank you in advanced & sorry for the bad English.