notify gives "

Question

I am using the nrfconnectSDK v2.4.0 and zephyr 
 
 i called the function shown below 
 int notify_results = bt_gatt_notify_cb(conn, &params); 
 with params containing 
 struct bt_gatt_notify_params params = {0}; params.attr = m_ble_metadata_response_attribute; params.data = (const void*)&command_data->command; params.len = (uint16_t)(command_data->parameter_length + 2); params.func = vsg_service_metadata_response_complete;

the m_ble_metadata_response_attribute 
 pointed to the last characteristic in my service. 
 
 and it failed with 
 <wrn> bt_gatt: gatt_notify: Device is not subscribed to characteristic 
 when i used nrfconnect on my iphone. 
 
 this is the end of my service. 
 they are my last two characteristics. 
 
 BT_GATT_CHARACTERISTIC(BT_UUID_CHR_METADATA_COMMAND, BT_GATT_CHRC_WRITE , BT_GATT_PERM_WRITE, NULL, write_metadata_command_cb, &m_queued_metadata_command), 
 BT_GATT_CHARACTERISTIC(BT_UUID_CHR_METADATA_RESPONSE, BT_GATT_CHRC_NOTIFY, BT_GATT_PERM_NONE, NULL, NULL, NULL),

then i added one more line to my service and it worked.!! 
 
 BT_GATT_CHARACTERISTIC(BT_UUID_CHR_METADATA_COMMAND, BT_GATT_CHRC_WRITE , BT_GATT_PERM_WRITE, NULL, write_metadata_command_cb, &m_queued_metadata_command), 
 BT_GATT_CHARACTERISTIC(BT_UUID_CHR_METADATA_RESPONSE, BT_GATT_CHRC_NOTIFY, BT_GATT_PERM_NONE, NULL, NULL, NULL), 
 BT_GATT_CCC(on_cccd_changed, BT_GATT_PERM_READ | BT_GATT_PERM_WRITE), 
 
 so my question is 
 
 Does the function bt_gatt_notify_cb(conn, &params); work correctly when the NOTIFY characteristic is the last characteristic in the service ? 
 thanks 
 phil