These is the cucumber scenario and the corresponding steps that I have the problem with

steps.rb

#  Scenario: Creating a product
#    Given I am logged in with role "admin"
#    When I follow "Admin-Panel"
#    And I follow "new product"
#    Then I should see "Please enter the new product data"

Given /^I am logged in with role "([^"]*)"$/ do |role|
  Factory.create(:user, name: "root")
  log_in "root"
end

Given /^I am viewing "([^"]*)"$/ do |path|
  visit path
end

When /^I follow "([^"]*)"$/ do |link_text|
  click_link link_text
end

Then /^I should see "([^"]*)"$/ do |text|
  has_content? text
end

def log_in(name, pass = "secret")
  visit "sessions#new"
  fill_in "name", :with => name
  fill_in "password", :with => pass
  click_button "LogIn"
end

# The errormessage:
# Given I am logged in with role "admin"
#  Scenario: Creating a product                           # features/products_admin.feature:6
#    Given I am logged in with role "admin"               # features/step_definitions/steps.rb:20
#    And I am viewing "admin/products"                    # features/step_definitions/steps.rb:16
#      undefined method `is_admin?' for nil:NilClass (NoMethodError)
#      ./app/controllers/application_controller.rb:31:in `is_admin?'
#      ./app/controllers/application_controller.rb:16:in `require_admin'
#      ./features/step_definitions/steps.rb:17:in `/^I am viewing "([^"]*)"$/'
#      features/products_admin.feature:8:in `And I am viewing "admin/products"'
#    When I follow "Neues Produkt"                        # features/step_definitions/steps.rb:33
#    Then I should see "Bitte neue Produktdaten eingeben" # features/step_definitions/steps.rb:49

# changes:
# - Added the log_in method
# - Altered the "Visit"-step with a "Follow"-one, now it seems to work, but why is that so? Why is the session canceled when using visit?