[exim] DKIM problem

Iḿ having problems with some particular incoming mails, the error
message is this:
DKIM: Error while running this message through validation, disabling
signature verification

This messages are stored on /var/spool/exim4/input but only the *-D file.

The mentions of dkim in my config_check_rcpt file are:
accept
hosts = :
control = dkim_disable_verify
accept
hosts = +relay_from_hosts
control = submission/sender_retain
control = dkim_disable_verify
accept
authenticated = *
control = submission/sender_retain
control = dkim_disable_verify

Thanks in advance, and sorry for my bad english!