title: How to solve a RubyMine "'ruby-debug-ide' isn't installed" error
body: <p>I get the error:</p>
  
  <pre><code>Cannot start debugger. Gem 'ruby-debug-ide' isn't installed or its executable script 'rdebug-ide' doesn't exist.
  </code></pre>
  
  <p>but all gems were successfuly installed:</p>
  
  <pre><code>gem 'ruby-debug-ide'
  gem 'debase'
  </code></pre>
  
  <p>I can run 'rdebug-ide' manually:</p>
  
  <pre><code>$ rdebug-ide
  Using ruby-debug-base 0.2.1
  Usage: rdebug-ide is supposed to be called from RDT, NetBeans, RubyMine, or
         the IntelliJ IDEA Ruby plugin.  The command line interface to
         ruby-debug is rdebug.
  </code></pre>
  
  <p>But when I start debugging, RubyMine asks to install the ruby-debug-ide gem. Why?</p>
  
  <p>And, after installation I get:</p>
  
  <pre><code>Cannot start debugger. Gem 'ruby-debug-ide' isn't installed or its executable script 'rdebug-ide' doesn't exist.
  </code></pre>
  
  <p>I'm running Mac OS X 10.11.3.</p>