Failed send access register: ME_ICMD_OPERATIONAL_ERROR

I am just getting started with BlueField-2 and DOCA and trying to run the example applications.
I am trying to create a Virtual Function by following the documentation on:
NVIDIA DOCA Virtual Functions User Guide
However, I am stuck at step #3 of chatper 2: Prerequisites which says to set the VFs to trusted mode by running this command on the DPU:
$ mlxreg -d /dev/mst/mt41686_pciconf0 --reg_id 0xc007 --reg_len 0x40 --indexes "0x0.0:32=0x80000000" --yes --set "0x4.0:32=0x1"
as the previous command fails with the following output:

root@ktdpu:~# mlxreg -d /dev/mst/mt41686_pciconf0 --reg_id 0xc007 --reg_len 0x40 --indexes "0x0.0:32=0x80000000" --set "0x4.0:32=0x1"
You are about to send access register id: 0xc007 with the following data:
Address    | Data
0x00000000 | 0x80000000
0x00000004 | 0x00000001
0x00000008 | 0x00000000
0x0000000c | 0x00000000
0x00000010 | 0x00000000
0x00000014 | 0x00000000
0x00000018 | 0x00000000
0x0000001c | 0x00000000
0x00000020 | 0x00000000
0x00000024 | 0x00000000
0x00000028 | 0x00000000
0x0000002c | 0x00000000
0x00000030 | 0x00000000
0x00000034 | 0x00000000
0x00000038 | 0x00000000
0x0000003c | 0x00000000

 Do you want to continue ? (y/n) [n] : y
 Sending access register...
-E- Failed send access register: ME_ICMD_OPERATIONAL_ERROR

any idea how to solve this problem ?

  1. Check VFs/Sfs on device by

    mst status -v
    /opt/mellanox/iproute2/sbin/mlxdevm port show

  2. Delete VFs/SFs

  3. Power cycle server/DPU

  4. Repeat below,
    Virtual Functions :: NVIDIA DOCA SDK Documentation