Most likely you have the Form set to "Continue Editing" and it is submitting, just doesn't look like it.
If you go to the Form > [Edit your form] > Data and see your entry then this is the case, and in the GEneral tab of your form there is the behavior when you submit, you want to probably set it to either the Redirect to a new URL or to display a message.
If you indeed do NOT see the item in the data, and it isn't actually submitting, first check the event log, and see if there are any errors. Also see if there are any required fields that you are not filling out, and if it's saving the PDF that your website's application pool has full control over the environment so it can actually save the submitted file to the file system. If it doesn't have write permission it may be erroring out mid save.