title: (Ubuntu 14.04) apt-get libopencv-dev, but get errors: Unable to correct problems, you have held broken packages
body: <p>Reading package lists... Done
  Building dependency tree<br>
  Reading state information... Done
  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:</p>
  
  <pre><code>The following packages have unmet dependencies:
   libopencv-dev : Depends: libopencv-objdetect-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libopencv-highgui-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libopencv-legacy-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libopencv-contrib-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libopencv-videostab-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libopencv-superres-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libopencv-ocl-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libcv-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libhighgui-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
                   Depends: libcvaux-dev (= 2.4.8+dfsg1-2ubuntu1) but it is not going to be installed
  E: Unable to correct problems, you have held broken packages.
  </code></pre>
  
  <p>also, I used "aptitude install libopencv-dev", but it did not work. So I don't know how to finished this problem.</p>