Sam s6 REading or writing cert error

hello i am trying to back up samsung s6 cert but its giving error,, if i try to write cert on s6 its giving error again
peration: Read CERT
Selected model: SM-G920F
Software version: 24.1

Waiting ADB device… OK
Reading phone info…
Model: SM-G920F
Android version: 6.0.1
Product code: SM-G920FZKAH3G
Phone version: G920FXXU4DPG4
PDA version: G920FXXS4DPH1
CSC version: G920FH3G4DPG1
CSC country code: UK
CSC sales code: H3G
HW version: MP 0.80V
Phone S/N: RF8G30VZALA
Modem board: SHANNON333
RF cal date: 20150310
Checking Super user right… true
Initialization AT RIL… error (0)

Done with Samsung Tool PRO v.24.1

please any solution