550 операций, не разрешенных использование FTP

Я использую FTP для управления некоторыми файлами на сайте, который я выполняю, но продолжаю видеть этот (усеченный) журнал ошибок:

Command:    DELE calendarpermission.php
Response:   550 calendarpermission.php: Operation not permitted
[...]
Command:    DELE button_down.gif
Response:   550 button_down.gif: Operation not permitted
Command:    CWD /domains/example.com/public_html/admincp
Response:   250 CWD command successful
Command:    PWD
Response:   257 "/domains/example.com/public_html/admincp" is the current directory
Command:    RMD control_examples
Response:   550 control_examples: Operation not permitted
Command:    CWD /domains/example.com/public_html
Response:   250 CWD command successful
Command:    PWD
Response:   257 "/domains/example.com/public_html" is the current directory
Command:    RMD admincp
Response:   550 admincp: Operation not permitted
Status: Retrieving directory listing...
Command:    PASV
Response:   227 Entering Passive Mode (122,155,5,50,138,244).
Command:    MLSD
Response:   150 Opening ASCII mode data connection for MLSD
Response:   226 Transfer complete
Status: Directory listing successful
Status: Set permissions of '/domains/example.com/public_html/admincp' to '777'
Command:    SITE CHMOD 777 admincp
Response:   550 CHMOD 777 admincp: Operation not permitted

Что я делаю для решения этого?