Unable to sign public key

[Joel]

Hello!

I am trying to sign a public key, but I get an error saying, `gpg: signing failed: No secret key`. However, a normal signing on a file works perfectly fine. I suspect it could be something because I have a yubikey and it might not work as I initially expected. Have anyone had similar problems and know how to fix it when you use a yubikey? 

Best regards,

Joel Lidin