Error enabling connection event extension in UART example

Hi all,

I use nRF52832 with the UART peripheral example.

I try to enable connection event extension in the device and get an error.

I use SDK V15.0.0 and Softdevice V 6.0.0

I put the following code at the end of the nrf_sdh_ble_default_cfg_set function:

    ble_opt_t  opt;
    memset(&opt, 0x00, sizeof(opt));
    opt.common_opt.conn_evt_ext.enable = 1;
    ret_code = sd_ble_opt_set(BLE_COMMON_OPT_CONN_EVT_EXT, &opt);

ret_code returns with 0x3001.

What am I doing wrong?

I'm am new to BLE and my knowledge is limited, specific detailed answers will be greatly appreciated.

Thank you