Shopping cart error in array when recovering last id sqlsrv_fetch_array 11- is not a Valid ss_sqlsrv_stmt Resource in

Question

I am mounting a shopping cart but am facing the following error I mentioned in the title. The method takes 2 parameter the $listProducts is an array as all purchase information and the $Total parameter receives $_SESSION of the total purchase amount. The First Insert works well, which is the creation of the order, then I select to retrieve the last order id to enter the order items. But when you enter if the $reg variable does not receive the value of the query and gives the following error...

sqlsrv_fetch_array(): 11 is not a Valid ss_sqlsrv_stmt Resource in

What I don’t understand is why it causes this mistake, because I don’t see any error in the code.

public function CriarVenda($listaProdutos, $Total){

        // criando venda
        $sql = "INSERT INTO CADPEDIDO(PED_DATA, VALORTOTAL)VALUES(?,?)";
        $params = array(date('Y-m-d'), $Total);
        $query = sqlsrv_query($this->con->Conecta(), $sql, $params);

        //resgatar última venda

        $sql = "SELECT MAX(CODIGO) FROM CADPEDIDO";
        $query = sqlsrv_query($this->con->Conecta(), $sql) or die( print_r( sqlsrv_errors(), true));

        $ultimavenda = 0;

        if($reg = sqlsrv_fetch_array($query)){
            $ultimavenda = $reg[0];
        }

        foreach($listaProdutos as $p){

            $sql = "INSERT INTO CADITENSPEDIDO(ITEM_PEDIDO, ITEM_COD_PEDIDO,ITEM_QTD ITEM_PRECO)VALUES(?,?,?,?)";
            $params = array($ultimavenda, $p->Codigo, $p->Qtd_comprado, $p->SubTotal);
            $query = sqlsrv_query($this->con->Conecta(), $sql, $params);

        }

 }