in the admin/orders_update.php page, change:
<input type="text" name="OrderTrackingURL" id="OrderTrackingURL" readonly="readonly" value="<?php echo(str_replace('"', '"', (isset($_GET['valid'])?ValidatedField("ordersUpdate","OrderTrackingNumber"):$row_WADAorders['ProviderTrackingURL']))); ?>" size="32" />
to:
<input type="text" name="OrderTrackingURL" id="OrderTrackingURL" value="<?php echo(str_replace('"', '"', (isset($_GET['valid'])?ValidatedField("ordersUpdate","OrderTrackingNumber"):$row_WADAorders['ProviderTrackingURL']))); ?>" size="32" />