... and this, in turn, means that you need to convert all your existing mod_alias directives (Redirect by that name) into mod_rewrite format. It generally isn't safe to mix modules.
But wait! If you've got a finite number of pages to redirect-- that is, "redirect A, B, C and D" rather than "redirect everything except E" --you may still be able to use mod_alias. You'll just need to change from Redirect alone, using straight text, to RedirectMatch using a Regular Expression.