Key keeps the old name after renaming it

[swart]

This is my code:\[code\]foreach ($all_orders as $order){//the $all_orders array contains a number of arrays, so it's a multidimensional array$order["Order Rank"]=$order[0];unset($order[0]);}\[/code\]after renaming the key with the new key and when i print the array:\[code\]print_r($all_orders);\[/code\]i got the old key name (which is 0):\[code\]Array( [0] => Array ( [0] => 1 )\[/code\]why it's not :\[code\]Array ( [0] => Array ( ["Order Rank"] => 1 )\[/code\]am i missing something? thanx in advance.