Syntax Error Debug – Unexpected T_CONSTANT_ENCAPSED_STRING [closed]-Collection of common programming errors

Trying to pull off a histogram of Quote Values in a shopping cart. This query works if I paste it directly into mySQL, however I am having problems with the PHP side of things.

Error message:

Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING in .../.../... Line 26.

My code:

echo '

Histogram of Quotes

';

$sql = 'SELECT 
            ROUND(ROUND(Fixes.FixAM/31.1035 * Products.Fineness * Products.Buy * Quotes.Weight, 2), -3)    AS bucket,
            COUNT(*) AS Count,
            RPAD('', LN(COUNT(ROUND(Fixes.FixAM/31.1035 * Products.Fineness * Products.Buy * Quotes.Weight, 2))), "*") AS bar
        FROM   
            Quotes,
            Products,
            Fixes,
            Currencies,
            Metals,
            ProductTypes
        WHERE
            Quotes.ProductId = Products.Id AND
            Products.MetalId = Metals.Id AND
            Products.ProductTypeId = ProductTypes.Id AND
            Fixes.CurrencyId = Currencies.Id AND
            Fixes.MetalId = Metals.Id AND
            Currencies.Code = "GBP"                     
        GROUP BY bucket';

$stmt = $db->prepare($sql); 
$stmt->execute();
    $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);  

Line 26 is the line which says GROUP BY bucket';

PROOF that SQL Code Works

bucket  COUNT   bar
0       114     *****
1000    37      ****
2000    8       **
3000    2       *
4000    3       *
5000    4       *
8000    1   
9000    1   
10000   1   
21000   1