title: Nuget package installed but references not resolved
body: <p>I have a multi-project solution with Prism Nuget packages installed in several projects. I then attempted to add a Prism Mef extensions package to one of the projects using the Nuget Package Manager UI (I have already added it to one of the other projects).</p>
  
  <p>The first time I attempted to add the package, it failed to install one of the dependencies, no specific error reason, just "failed". So, I installed it a second time, all seemed to be fine, no errors reported, but a few of the references did not resolve.</p>
  
  <p>So, I uninstalled the package and all dependencies and installed it again. Again all appeared fine, but more references do not resolve.</p>
  
  <p>I have tried uninstalling and installing the package more times but get the same result every time now.</p>
  
  <p>I have had this problem many times and I know its not specific to the Prism package as I've had it with loads of different packages.</p>
  
  <p>I think its just a major bug with Nuget, but I'm hoping somebody will know an easy way to fix it. I think I usually have better success with the Nuget console, but I find it more effort to use.</p>
  
  <p>I've done some searching online and not really found a good explanation of the cause of the problem or a way to resolve it.</p>
  
  <p>Somebody at work completely refuses to have anything to do with Nuget as he has so many of these issues, but I am determined to make it work!</p>