sm-g935f read cert problem

Hi, when i try to read cert on the g935f it give me this error:

Welcome to Octoplus/Octopus Box Samsung software version 2.3.7
To connect SM-G935F phone you have to perform the following steps:
1. Disconnect USB cable from phone.
2. Go to Menu->Settings->More->About Device.
3.Tap on "Build number" 7 times to enable developer options.
4. Go to Menu->Settings->More->Developer options.
5. Turn on "USB Debugging" option.
Platform: Samsung Android
Selected port: COM11
Selected model: SM-G935F
Detected phone model: SM-G935F
Firmware compiled date: Tue Aug 9 18:50:34 KST 2016
PDA version: G935FXXU1BPH6
CSC version: G935FWIN1BPH1
SW version: G935FXXU1BPH1
Phone SN: RF8H334TXKN
Android version: 6.0.1 (MMB29K)
Sales code: WIN
Country: ITALY
HW platform: exynos5
HW Chip: exynos8890
HW Modem: SHANNON335
Codename: hero2ltexx
Checking Root:
Phone is Rooted.
Reading security backup, please wait…
Backup saved as C:\Program Files\Octoplus\Octoplus_Samsung
Initializing exploit…
Executing exploit…
Exploit has been executed successfully
Reading Certificate…
Checking Certificate file…
Checking Certificate failed
Reading Certificate failed
Performed by 2.3.7 Software version.

I have flashed firmware on the phone but result is the same, anyone can help me?

thanks in advance