title: Error adding webpart
body: <p>I'm developing a webpart in Sharepoint 2013 using VS2012. In this webpart I'm using a custom dll that I created. The library framework is 4.0 and the visual webpart framework is 4.5. </p>
  
  <p>The problem is when I'm adding the webpart in sharepoint page, the following error appeared:</p>
  
  <pre><code>Could not load file or assembly 'RulesDll, Version=1.0.0.0, Culture=neutral, PublicKeyToken=d2371e81bc184aa5' or one of its dependencies. The system cannot find the file specified
  </code></pre>
  
  <p>Searching in google I found a lot of solutions to resolve this problem</p>
  
  <ul>
  <li><p>Adding library to GAC using two methods.</p>
  
  <p>(1) gacutil -i RulesDll.dll</p>
  
  <p>(2) Using package ---> Advanced options in the solution explorer in VS2012</p></li>
  </ul>
  
  <p><img src="https://i.stack.imgur.com/U29SZ.jpg" alt="enter image description here">  </p>
  
  <p>When I running gacutil -l RulesDll in VS command prompt everything sames to work:</p>
  
  <pre><code>Microsoft (R) .NET Global Assembly Cache Utility.  Version 4.0.30319.17929
  Copyright (c) Microsoft Corporation.  All rights reserved.
  
  The Global Assembly Cache contains the following assemblies:
    RulesDll, Version=1.0.0.0, Culture=neutral, PublicKeyToken=d2371e81bc184aa5,    processorArchitecture=x86
  </code></pre>
  
  <p>Number of items = 1</p>
  
  <p>So the library is in the GAC.</p>
  
  <ul>
  <li>Adding the library to the save control in web.config</li>
  </ul>
  
  <p>But nothing works. Does someone know why it's impossible to add my own webpart in a sharepoint page?</p>