Failed to execute velocity into pdf view

Tested on a local instance of XE 7.4.2

1.Login as Admin and create a page.
2. Add this code as its content:

{{velocity}}
#set($docsToExport = ['Blog.BlogIntroduction', 'Sandbox.WebHome', 'Sandbox.TestPage1'])
$services.pdfexporter.export("My test pdf", $docsToExport, true, false)
{{/velocity}}

3. Save the page.

Actual result:

• After you save the page, you re redirected to PDF view
• But, instead of displaying the mentioned pages, you will get:
  Failed to execute the [velocity] macro

Expected Result:

• i expect to be able to see all the pages mentioned in the script ((Blog.BlogIntroduction', 'Sandbox.WebHome', 'Sandbox.TestPage1) that are by default created in xwiki.