directoryentry.invoke("changepassword") the max password length

I've met a error when I try to update the password of the user from Active Directory by invoke method

DirectoryEntry.Invoke("changepassword", object[]{oldPassword, newPassword})

The new password is complex enough and can update the password successfully when the length of the new password is less than 63(include 63), but when the length of the new password is larger than 63, one error happened. The error message is:

Unable to update the password. The value provided for the new password does not meet the length, complexity, or history requirement of the domain.(Exception from HRESULT: 0x8007052D).

The code is:

public static void ChangePassword(DirectoryEntry user, string oldPassword, string newPassword)       
{              
    oldPassword = (oldPassword == null) ? string.Empty : oldPassword;
    newPassword = (newPassword == null) ? string.Empty : newPassword;
    if (oldPassword != newPassword)
    {
        user.Invoke("ChangePassword", new object[] { oldPassword, newPassword });
    }
}

I don't know why it happened now, does anyone know that? thank you!