pop up seems not working

Hello, I installed the catch popup plugin. Now I want to add the plugin to a special page (to give explanation about page content). In the editor bar I use the pop up button. After that the code occurs on the page. Next is saving the page. After that I can see the page not with a plugin in, but with html code like: < class="catch-popup-trigger catch-popup-490 " style="cursor: pointer;" data-popup="490”> Probably I make a very simple mistake. Kind regards Hans Hagmeijer