newbee q?

Hi,
I am learning to write a driver for linux OS.
I am reading O'Reilly book for this purpose.

I am getting the following error when i do "insmod"
##insmod -f skull.o
##skull.o: couldn't find the kernel version the module was compiled for


Below is my code:
**************
#define MODULE
#include <linux/ioport.h>
#include <linux/errno.h>
#include <linux/init.h>


static int port = 0x2080,range=200;
static int skull_detect(unsigned int port, unsigned int range)
{
int err;

// if((err =check_region(port_range)) < 0) return err;
/* if(skull_probe_hw(port_range) != 0) return -ENODEV; */
request_region(port,range,"skull");
return 0;
}

static void skull_release(unsigned int port,unsigned int range)
{
release_region(port,range);
}

int init_module(void)
{
int rc;
printk("<1> .... Inside Init.... \n");
rc = skull_detect(port,range);
printk("<1> rc = %d",rc);
return 0;
}

void cleanup_module(void)
{
printk("<1>..... Exit Module ....\n");
skull_release(port,range);
}
*********************

Could anyone suggest me what could be the problem...

Thanks
Uday