title: Namespace dependencies not required
body: <p>I am trying to build an R package so reading the manual on CRAN.
  I could figure out that using imports to load functions in your namespace would be the best bet to use in the Description file.
  After adding to the description file, I also added it to the namespace file.
  I added importFrom to the namespace file with the functions required.</p>
  <p>Now when I run R CMD check on my package,
  I get an ERROR as</p>
  <blockquote>
  <p>Namespace dependencies not required :
  'ggplot2'</p>
  </blockquote>
  <p>Further information : Even if I add the package to the Depends in the description file, they are not getting loaded.</p>
  <p>Please help with this.</p>
  <p>Please find my description file below</p>
  <pre><code>Package: bigpackage
  Type: Package
  Title: Some title
  Version: 1.0
  Date: 2012-10-25
  Author: Mayank Bansal
  Maintainer: somename
  Imports : R(&gt;= 2.15.1), SweaveListingUtils( &gt;=0.5.5),xtable(&gt;=1.7-0),
          brew(&gt;=1.0-6), knitr(&gt;=0.8), RHive(&gt;= 0.0-6), ggplot2(&gt;=0.9.2)
          , brew, knitr
  SystemRequirements : LaTeX(texi2dvi) must be present in the system to
          create PDF reports
  Description: Some Description
  License: file LICENSE
  LazyLoad: yes
  ByteCompile: true
  OS_type : unix
  </code></pre>