Create Jail fail by c language

[freekai]

  This is My Code:

  1	#include<sys/param.h>
  2 #include<sys/jail.h>
  3 #include<arpa/inet.h>
  4 #include<stdio.h>
  5 #include<errno.h>
  6 
  7 int main()
  8 {
  9     int jid;
 10     struct jail j;
 11     struct in_addr ip4;
 12     const char *cp="192.168.1.10";
 13 
 14     j.version=JAIL_API_VERSION;
 15     j.path="/home/mk/jail";
 16     j.hostname="testJail";
 17     j.jailname="test";
 18     j.ip4s=inet_addr(cp);
 19     j.ip6s=0;
 20 
 21     if(1!=inet_aton(cp,&ip4))
 22         printf("the address is invalid\r\n");
 23 
 24     j.ip4=&ip4;
 25     j.ip6=NULL;
 26 
 27     jid=jail(&j);
 28 
 29     switch(errno){
 30         case EPERM:
 31             printf("eperm\r\n");
 32             break;
 33         case EFAULT:
 34             printf("efault\r\n");
 35             break;
 36         case EINVAL:
 37             printf("einval\r\n");
 38             break;
 39 
 40         case EAGAIN:
 41             printf("eagain\r\n");
 42     }
 47     return 0;
 48 }

 The problem is it will print `einval`,it means `The version number of the argument is not correct.`
 How to solve it?