Using evil-leader with use-package: Error (use-package): evil-leader/:config: Invalid function: (global-evil-leader-mode)

I'm trying to add use-package to my init.el and I'm running into this error:

Error (use-package): evil-leader/:config: Invalid function: (global-evil-leader-mode)

Here's a stripped down init.el that produces that error (assumes evil and evil-leader are already installed)

(package-initialize)

(require 'use-package)

(use-package evil :ensure)

(use-package evil-leader
  :ensure
  :after evil
  :config
  ((global-evil-leader-mode)
      (evil-leader/set-leader ",")
      (evil-leader/set-key
        "b" 'buffer-menu)
      ; Apparently this needs to go after (global-evil-leader-mode)
      ; https://emacs.stackexchange.com/questions/30332/evil-leader-stops-working-when-i-eval-buffer
      (evil-mode t)))

This is how it was set up without use-package working correctly:

(package-initialize)

(require 'evil)

(require 'evil-leader)
(global-evil-leader-mode)
(evil-leader/set-leader ",")
(evil-leader/set-key
  "b" 'buffer-menu)
; Apparently this needs to go after (global-evil-leader-mode)
; https://emacs.stackexchange.com/questions/30332/evil-leader-stops-working-when-i-eval-buffer
(evil-mode t)

Any help identifying what I'm doing wrong would be appreciated, thank you!

I thin you should remove the parenthesis after :config