i get an mysql on the fetch array

[webcoder]

i keep getting this error, can you please check it out..
Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result

heres the code...

function get_id($sel_id) {
global $connection;
$query = "SELECT * ";
$query .= "FROM post ";
$query .= "WHERE id=" . $sel_id ." ";
$query .= "LIMIT 1";
$result = mysql_query($query);
if ($sub = mysql_fetch_array($result)) {
return $sub;
} else {
return NULL;
}
}

[bradgrafelman]

You should be checking the return value of [man]mysql_query/man to see if an error occurred. See the link in my signature for an explanation.

[webcoder]

could you possibly correct the error for me so i can use?