Upload file doesn´t work

Hi, I have a problem with a file uploaf field.

Users and admins have the same problem. When you try to upload a file, aparently systems says that the upload was succesful. And if you go to the folder, there it is the file. But the Mysql BBDD doesn´t register the name of the uploaded file. And so on, the field appears to be empty... Don´t understand what happens. The rest of the fields, even other to upload images, works fine.

Any ideas?

Enable debug mode and maximum error reporting in Joomla global configuration then retry and see if any errors output.