Modal popup disappears

I have created a button and on the click of that button a javascript code gets trigerred. I have given the link of a list of sharepoint that gets opened as a modal dialog box on the click of that button. I am facing a problem in opening that modal popup. Whenever I click on the button the modal popup opens but only for a fractions of seconds and then gets closed automatically.

Please suggest a way to display that modal dialog box.