FortiWeb 6.4.0 - exporting private key

Hi,

Long story short:

I have created CSR on Fortiweb, CSR was signed and cerficate was imported on FortiWeb

My question is:

Is it possible to export private key and import it to the backend server? 

The probilem I see here is:

Private key is password encrypted (duh?), but there is no option to specify password during CSR creation, so I guess the password is automatically generated during CSR creation. I tried changing the password in CLI:

conf sys cert local

edit "cert1"

unset passwd

set passwd somepassword

end

but I get an error:

Command fail. The configuration of a certificate can not be changed from CLI except the comments.

Am I missing something here? Or this is just not possible?