PHP mkdir failure solution under Linux ____linux

Recently to do a Web site, the background requires users to manually create folders, after the site was written, running very well under Windows, the results of a problem on the server, in the manual creation of folders, there is no error, but into that directory, but do not see the corresponding folder created, should code execution problems. The code is as follows:

mkdir ($path, 0777);
The IF (file_exists ($path))
      Echo directory was created successfully. ";
Else
      Echo failed to create the directory. ";

Suspect is a permission issue, so the login server under root to create folder directory authorization: chmod 777 Parpath, and then run the code, all OK.

Note: Parpath is the parent directory, and Path is the subdirectory to be created.