I've a folder, in which there is a file. I want user to have full control on a specific file, and should be denied every access to the other files. The first thing I did was to disable inheritance of permissions for this folder. Then I added Full Control on the specific file. Everything seems good except that the user can't save(Write) to the file, although write permissions are given. Any idea where may be the problem
Are your users accessing the file via a share? What are the share permissions set to? Your users will need at least the Modify share permission in order to write to the file.
One thing you can try as well is to use the Effective Access tab in the advanced security options of the file. It will tell you exactly what file permission the users have (but not share permissions).