Hello, friends.
I'm trying to setup ssh using public/private key on Cisco router.
1) I launch puttygen. Press "Generate" button.
After key genereating, I get following

2) In the "key passphrase" and "Confirm passphrase" I entered "cisco".
3) After that, I click "save public key" button and save public key in the folder on the desktop of my windows PC.
3) Than I click "save private key" button and save private key in the sane folder.
4) After that I go to the CLI of my router and do following:
Router(config)#ip domain-name cisco.com
Router(config)#crypto key generate rsa modulus 1024
Router(config)#ip ssh version 2
Router(config)#ip ssh pubkey-chain
Router(conf-ssh-pubkey)#username denis
Router(conf-ssh-pubkey-user)#key-string
Router(conf-ssh-pubkey-data)#<here I copy and paste public key, that was generated by puttygen>
Router(conf-ssh-pubkey-data)#exit
Router(conf-ssh-pubkey-user)#exit
Router(config-ssh-pubkey)#exit
Router(config)#
5) Than I add my private key in Putty settings.
But when I trying to connect to router using putty, I'm getting following error

6) Why Cisco Router refuse my private key?
Because in the "show run" output of my router I can see, that finerprint is the same as in the puttygen output

Also, the output of "show ip ssh" show correct public key, that was generated by puttygen and that was pasted in the configurtion of the router.
Help. please. What I'm doing wrong.
Thanks.