Centos – Bind DNS not working

I Know there always lots of answer about Bind. But somehow I can't understand the problem of my settings.

Here is my configuration

options {
     listen-on port 53 { 192.168.159.130; };
     listen-on-v6 port 53 { ::1; };
     directory      "/var/named";
     dump-file      "/var/named/data/cache_dump.db";
     statistics-file "/var/named/data/named_stats.txt";
     memstatistics-file "/var/named/data/named_mem_stats.txt";
     allow-query     { any; };
     recursion yes; }

zone "example.com" IN {                                    
    type master;
   file "example.fz";                                             
   allow-update { none; }; };

zone "159.168.192.in-addr.arpa" IN {                    
     type master;
     file "example.rz";                                            
     allow-update { none; };
};

# /var/named/example.fz file

$TTL 1D
@     IN SOA     @ example.com. (
                         0     ; serial
                         1D     ; refresh
                         1H     ; retry
                         1W     ; expire
                         3H )     ; minimum

           IN          NS   ns1.example.com.           
           IN          A     192.168.159.130             
ns1        IN          A     192.168.159.130 

# /var/named/example.rz file

$TTL 1D @ IN SOA @ rname.invalid. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum

          IN     NS         ns1.example.com.
          IN     A          192.168.159.130
130       IN     PTR      ns1.example.com.    

# /etc/resolv.conf

search example.com
nameserver 192.168.159.130

# Test results

[root@localhost named]# named-checkconf /etc/named.conf
[root@localhost named]# named-checkzone example.com /var/named/example.fz
zone example.com/IN: loaded serial 0
OK
[root@localhost named]# named-checkzone example.com /var/named/example.rz
zone example.com/IN: NS 'ns1.example.com' has no address records (A or AAAA)
zone example.com/IN: not loaded due to errors.

nslookup example.com
Server:     192.168.159.130
Address:    192.168.159.130#53

** server can't find example.com.example.com: SERVFAIL

I have used exact same setting before and as far I remember worked fine.But not now !
Hopefully someone could point at something.

Note: I have restarted bind several times.