How to get notifications from GATT Server BX3105

Hi there,

I am communicating to nRF Connect android application using BX3105 BLE. And I have setup my BX3105 as GATT server. My primary service is ‘cccc’ and using which I have added two custom characteristics for Tx and Rx, which is ‘dddd’ and ‘eeee’ respectively.
ie) For Rx, AT+SRBLEADDCHAR=40,“eeee”,4,16,20,1,“M”,1
For Tx, AT+SRBLEADDCHAR=40,“dddd”,16,17,20,1,“Z”,0
Then I added a characteristic descriptor iE) CCCD to the above characteristics,
after that, I have tried to Notify, GATT client using
I am getting ‘OK’ response from BX3105. But I can’t see the notification from nRF Connect application even though I tried Enable CCCD.
I can see the log that “Unable to configure notifications for 0000dddd-0000-1000-8000-00805f9b34fb”
Please let me know what I am missing / what I have to do from BX3105 in order to get the notification. Thanks in advance.