title: jenkins how can I trigger builds when there is a change on gitlab
body: <p>I am trying that Jenkins build my project when there is a change in my GitLab repository. I checked the option</p>
  
  <pre><code>Build when a change is pushed to GitLab. GitLab CI Service URL: http://172.172.10.21:8090/project/myproject/myproject_frontend
  </code></pre>
  
  <p>and the suboptions</p>
  
  <pre><code>Push Events 
  Merge Request Events
  Rebuild open Merge Request
  Comments
  Comment for triggering a build
  </code></pre>
  
  <p>Also I checked</p>
  
  <pre><code>Check repository (SCM)   ((without schedules))
  </code></pre>
  
  <p>It does not work like this. </p>
  
  <p>what is missing??</p>
  
  <p>thanks in advance</p>