CVS 无法更新

我的CVS死活更新不了，也不能添加内容，但是能提交。报如下错误：
cvs server: invalid RCS expansion flags
Valid flags are one of:
t Text file (default)
b Binary file (merges not allowed).
u Unicode (UCS-2) file.
Followed by any of:
k Substitute keyword.
v Substiture value.
l Generate lockers name.
o Don't change keywords.
L Generate Unix line endings on checkout.
(Specify the --help global option for a list of other help options)

错误，CVS操作失败

如何解决 ？