[exim] if or condition has me confused

warn condition = ${if or {\

                      {exists{$acl_m_domain_directory/some-sa}}\
                      {exists{$acl_m_user_directory/some-sa}}\
                      }{yes}{no}}
     set acl_m_sa_reject_level = 210

Condition always returns true even when both files do not exist.

What am I missing?

Thanks in advance