BLE characteristic notification issues

Hi guys,

I have two characteristics, one for get values from mobile application

and the second one is to reply as notification to user, to the mobile application.

I registered to notification characteristic, to reply the user for any changes.

I have two issues with Characteristic Notification.

1. From some reason, when the mobile application send to the write characteristic an array of more than about 25 bytes, and than I send a notification, the result of the function is ok, but the application doesn't receive the notification. If I send less than about 25 bytes, the application receive the notification message.
2. When the application send a short array f bytes (let say around 10), the application receive the notification, BUT if the application send again a short array of bytes, the application doesnt get the notification.

This is code of the notification character:

 aci_gatt_add_char(AdminService.AdminServiceHenale,
 UUID_TYPE_128, &uuid16,
 100,
 CHAR_PROP_NOTIFY,
 ATTR_PERMISSION_NONE,
 GATT_NOTIFY_READ_REQ_AND_WAIT_FOR_APPL_RESP, /* gattEvtMask */
 7, /* encryKeySize */
 1, /* isVariable: 1 */
 &(AdminService.ConfigStatusHandle));

and this is the sending of the notification:

 result = aci_gatt_update_char_value(AdminService.AdminServiceHenale,
 AttrHdle,
 0, /* charValOffset */
 len, /* charValueLen */
 (uint8_t *) pPayload);

Thank you for your help!