Default image using php, can't tell if its catching id - php

Question

i'm trying to relay the id through this if statement to see if the file exits. If it does I want to use the id to grab that image from the corporation-logos/ folder. If not i'd like to simply show a default image. I can't tell if its catching the id or not as it keeps spitting out the default.
if ($productCount > 0) {
// get all the product details
while($row = mysql_fetch_array($sql)){
$id = $row["id"];
$imgStock="http://www.stocksandstocks.com/corporation-logos/$id.jpg";
$http_image="http://www.stocksandstocks.com/images/no-logo-default.png";
if(file_exists($imgStock))
{
$imgPick = "$imgStock";
}
else
{
$imgPick = "$http_image";
}
echo "
<ul>
<li>
<div class='wrapPicks'>
<div class='symbolPicks'>
<div class='quoteTitle'>$quoteTitle</div>
</div>
<div class='bgPicks'>
<img src='$imgPick' height='50px' widht='80px' alt='stock symbol $quoteTitle logo' />
<div class='separateWrap'>
<div class='quote'>
<b>Entry Price:</b> $$entry
</div>
<div class='quote'>
<b>Last trade:</b> $$lastPrice
</div>
</div>
<div class='quoteReturn'>
<b>Open P/L:</b>
<div class='bigGreen'>
<span style=\"color: $color\">$positive $$profit </span>
</div>
</div>
</div>
</div>
</li>
</ul>";