Hi,
Maybe you have a mandatory field which is not filled.
What also may happen is there's an error which message is not displayed because of the template you use.
If you can access the form on edition, it means you have the permissions to, so it's not a problem with editing permissions.
You could may be try to remove or put some fields of the form in 'clear' access to avoid them to be loaded and see what happens when you save your content. if it works, publish back one field at a time and keep testing.