Service Notification problem - BLE_ERROR_INVALID_ATTR_HANDLE

Question

Hello everyone, 
 I am trying to enable notification on a characteristic based on the code example from nAN36.
Unfortunately the sd_ble_gatts_hvx() function returns: 
 BLE_ERROR_INVALID_ATTR_HANDLE - "Invalid attribute handle(s) supplied. Only attributes added directly by the application are available to notify and indicate." 
 I can't quite get the meaning of the "attributes added directly by the application". Any ideas how to interpret that or general guidelines how to approach this problem? 
 The setup is: ARMGCC + S110 + 51822.
I am testing it with the nRF Master Control Panel, where it says that the notifications are enabled. 
 Thank you in advance!

Petter Myhre · Accepted Answer

Services, characteristics and descriptors are attributes. You add them by with 
 sd_ble_gatts_service_add()
sd_ble_gatts_characteristic_add()
sd_ble_gatts_descriptor_add() 
 These return the attribute handles that are use in the attribute table. 
 So when you call sd_ble_gatts_hvx() you need to ensure that you use the correct attribute handle of the characteristic value that you want to send a notifcation from.