Why wont this work?

[Jalrock]

<?php
include "store_include.php";
////----INDIVIDUAL PRODUCT VIEW ---------------------///
if ($prodid) {
$product = '';
    $sql = $DB_site->query = "SELECT * FROM product WHERE prodid=$prodid";
    $result = mysql_query($sql);
    $myrow = mysql_fetch_array($result);

    $prodid = $myrow["prodid"];
    $prodname = $myrow["prodname"];
    $image = $myrow["image"];
    $price = $myrow["price"];
    $cost = $myrow["cost"];
    $sellerusername = $myrow["username"];
eval("\$product .= \"".gettemplate("store_productbit")."\";");
////----END INDIVIDUAL PRODUCT VIEW ---------------------///  
////----VIEW BY CATAGORY---------------------------------///
} elseif ($cat) {
$catbit = '';
    $sql = $DB_site->query = "SELECT prodid,prodname,image,price,cost,username FROM product WHERE catid='$catid'";
    $result = mysql_query($sql);
    while ($myrow = mysql_fetch_array($result)) {

    $prodid = $myrow["prodid"];
    $prodname = $myrow["prodname"];
    $image = $myrow["image"];
    $price = $myrow["price"];
    $cost = $myrow["cost"];
    $sellerusername = $myrow["username"];
    
eval("\$catbit .= \"".gettemplate("store_catbit")."\";");
}
////----END VIEW BY CATAGORY---------------------------------///

  }else{
$content = '';
$sql = $DB_site->query = "SELECT * FROM product";
    $result = mysql_query($sql);
    while ($myrow = mysql_fetch_array($result)) {

    $prodid = $myrow["prodid"];
    $prodname = $myrow["prodname"];
    $image = $myrow["image"];
    $price = $myrow["price"];
    $cost = $myrow["cost"];
    $sellerusername = $myrow["username"];

eval("\$content .= \"".gettemplate("store_contentbit")."\";");
}
}

eval("dooutput(\"".gettemplate('store_main')."\");");
?>

This is the error I get if you try to view by catagory.

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/twins-cl/public_html/forum/store_index.php on line 23

[mr e]

im pretty sure this doesn't work

PHP Code:

$sql = $DB_site->query = "SELECT prodid,prodname,image,price,cost,username FROM product WHERE catid='$catid'";
    $result = mysql_query($sql); 


try this

PHP Code:

$result = $DB_site->query("SELECT prodid,prodname,image,price,cost,username FROM product WHERE catid='$catid');