Silverstripe UploadField Extension is not allowed

If you get this error when you try to upload a fileĀ  and you already have added the extension to setAllowedExtentions.

UploadField::create( 'UploadFile' )
  ->setAllowedExtensions( array( 'ods' ) );

Extension is not allowed (valid: , ace, arc, arj, asf, au, avi, bmp, bz2, cab, cda, css, csv, dmg, doc, docx, dotm, dotx, flv, gif, gpx, gz, hqx, ico, jar, jpeg, jpg, js, kml, m4a, m4v, mid, midi, mkv, mov, mp3, mp4, mpa, mpeg, mpg, ogg, ogv, pages, pcx, pdf, pkg, png, potm, potx, pps, ppt, pptx, ra, ram, rm, rtf, sit, sitx, svg, tar, tgz, tif, tiff, txt, wav, webm, wma, wmv, xls, xlsx, xltm, xltx, zip, zipx)

Added these lines to /mysite/_config/config.yml

File:
  allowed_extensions:
    - ods