Using company-mode completion with read-from-minibuffer

Question

The following code (mostly coming from here) creates a company-mode back-end and binds TAB to it:

(require 'company)

(defconst sample-completions
  '("procedural" "functional" "high-level" "low-level" "statically-scoped" "dynamically-scoped"))

(defun company-sample-backend (command &optional arg &rest ignored)
  (interactive (list 'interactive))
  (let ((my-completions (copy-sequence sample-completions)))
    (case command
      (interactive (company-begin-backend 'company-sample-backend))
      (prefix (and (eq major-mode 'fundamental-mode)
           (company-grab-symbol)))
      (candidates
       (remove-if-not
        (lambda (c) (string-prefix-p arg c))
        my-completions)))))

(add-to-list 'company-backends 'company-sample-backend)

(define-key company-mode-map (kbd "TAB") 'company-sample-backend)

I have checked that the above works. That is, when I put a regular buffer (such as *scratch*) in company mode, I can invoke completion by pressing TAB and the sample-completions collection is used for completion.

Now I am trying to read a string from mini-buffer with auto-completion. To make sure that the mini-buffer is in company mode, I evaluate:

(defun my-minibuffer-mode ()
  (company-mode 1))
(add-hook 'minibuffer-setup-hook 'my-minibuffer-mode)

Now I try:

(read-from-minibuffer "Prompt: ")

However, what I get is completion from the English dictionary and not from my sample-completions collection. How do I fix this?