pureftp创建用户报错

[root@Pengpeng configuration-file]# /usr/local/pureftpd/bin//pure-pw useradd ftpuser1 -uuser3 -d /tmp/tfp                                                               Password:
Enter it again:
Error.
Check that [ftpuser1] doesn't already exist,
and that [/etc/pure-ftpd/pureftpd.passwd.tmp] can be written.