Frontend file uploads not working

I have a static super table field where logged in users should be able to upload one image to the super table field. With my form I can save my text values but I cannot save my image. Here is my form (simplified): <form method=”post” accept-charset=”UTF-8″ enctype=”multipart/form-data”> <input type=”hidden” name=”action” value=”entries/save-entry”> <input type=”hidden” name=”redirect” value=”filed/{slug}”>…