freebsd security - May 2003 - Problem with -c switch for ssh-add in OpenSSH 3.6.1 on CURRENT

Hi,

I tried to use this new -c switch for ssh-add, which makes ssh-agent
ask every time particular key is going to be used for user's
permission. It seems to fail for me. When I add some key to the agent
and logon to remote host, I get this message when ssh tries to
authenticate the user: "Agent admitted failure to sign using the key".
The key added to agent without the -c switch works, of course. The
SSH_ASKPASS variale is set to ssh-askpass, which also works for me.
What might be the problem?

/S