help me about this issue

[rockyford1000]

i tried to make a dynamic director by the use of php in the plesk.
it works when you just add the first folder but if you make another one inside the dynamic folder it will not work..
this error will appear..
"Unable to create directory /httpdocs/yazola360/rocky/bvcvb: filemng failed: mkdir: cannot create directory `/var/www/vhosts/yazola.com/httpdocs/yazola360/rocky/bvcvb': Permission denied filemng: Error occured during /bin/mkdir command." what does it mean...pls help me