Unusable secret key (adduid)

[Ivan Markin]

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Hash: SHA256

Hello!

I'm using OpenPGP card to store my secret keys on it. Now I'm adding a
new UID to my key by running gpg2 --edit-key. What I've got is this
strange error:

gpg (GnuPG) 2.0.25; Copyright (C) 2013 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Secret key is available.

gpg: using PGP trust model

... there my keys ...

gpg> adduid
Real name: GPG User
Email address: user at gnupg.org
Comment:
You selected this USER-ID:
    "GPG user <user at gnupg.org>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
gpg: secret key parts are not available
gpg: signing failed: Unusable secret key

How to solve this?

Thank you,
Ivan Markin
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Version: GnuPG v2
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

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