Actually it is good to ask, as it is a common error on grocery CRUD when there is a JavaScript error.
This is mainly a problem when there is a JavaScript error at the previous page.
For example when you are at your add form . For example: http://www.grocerycrud.com/demo/offices/add check your firebug to see if there is any JavaScript error. This is mostly happen when you have the jquery or the jqueryUI already at your JavaScripts . If so then to prevent the conflict, a simple line of code can release you from the searching. You can simply do:
$crud->unset_jquery(); //This will unset the Jquery library to load
or:
$crud->unset_jquery_ui(); //This will unset the Jquery UI library to load
If you are still having problems, check your JavaScripts and try to remove some plugins that can cause this problem. Some times it happens when the Twitter Bootstrap is installed, but just the unset_jquery() method could do the job.
And something lastly I am not sure but I think that the latest grocery CRUD version is not compatible with Jquery v.1.9.0 . So if you are using Jquery 1.9.0, try to switch to a previous version e.g. 1.8.3 or you have to wait for the major release of grocery CRUD v.1.4 that will support Jquery v.1.9.0 .