title: Don't work Push to Stack in C#
body: <p>For my Stack I use:</p>
  
  <pre><code>private Stack stOperations = new Stack();
  </code></pre>
  
  <p>So, when Stack constains only one element (Stack[0] = "false" (this is string)) and I try to push using:</p>
  
  <pre><code>stOperations.Push(neededIDs.Contains(element) ? "true" : "false");
  </code></pre>
  
  <p>Where <code>neededIDs.Contains(element)</code> = false.. nothing happens. Stack doesnt change! I know that because I see that in VS debugger:</p>
  
  <p><img src="https://i.stack.imgur.com/khkut.png" alt="stack in debugger"></p>
  
  <p>Explain me, please, where am I wrong? </p>