problems in chflags

[smux at terra.com.br (Smux)]

Hi all!
I'm getting errors on my server, and would like o try fix this, by that way:
Verifing errors on my server, I found that someone root called command "chflags sappnd /etc/master.passwd" returning that error:

[root_(_at_)_centerbr /etc]$ chflags nosappnd master.passwd
chflags: master.passwd: Operation not permitted

Someone can help me how do like to try fix this this problem?
Thanks.