could not able change permission of /home dir

Hi

i am new to this admin area .

i have created user with name as "ab" and gave home dir as /home/ab .

when i tried to create the /home/ab dir , i got he following error.
"mkdir: Failed to make directory "/home/ab"; Operation not applicable
"

Thanks in advance .

may be home directory mount by automountd and lock

try this

/sbin/init.d/autofs stop