First, open the Javascript console within your browser.  Each browser is different, so check out this link for instructions on your browser:

https://webmasters.stackexchange.com/questions/8525/how-do-i-open-the-javascript-console-in-different-browsers

Be sure you have the "Console" tab highlighted:

If errors are present, they appear in red and can be expanded by clicking the little arrow on the left:

Send us the text or a screenshot of this to help us solve your issue!