I am not able to add files to the Digital Library via the “Uploader”.

You may be uploading a file of an unsupported file type. 

Check the file type with those that the uploader supports:

• Images: jpg, jpeg, png, gif.
• Videos: 3g2, 3gp, asf, Avi, Flv, m2ts, m4v, m4v, MOV, MPEG, mpeg4, mpg, ts, vob, WMV, mp4, webm.
• Audios: mp3, Ogg, m4a, wav.