Please help to solve error return code:LE_ERR_IO of subroutine errlog_find_first

Enviroment:AIX V5.2
compile:IBM VAC enterprise V7.0

programe code:

root@zhguowen_sv:/asmdev/asm#cat errlog_find.c

Code:

#include <stdio.h>
#include <fcntl.h>
#include <sys/errlog.h>

int mode=0;
unsigned int magic;

errlog_handle_t errlog_va;
errlog_handle_t *hdl=&errlog_va;

int begintime=0710000007,endtime=0727000007;
/*MMDDHHMMYY (month, day, hour, minute, and year).*/

main()
{
	magic=LE_MAGIC;
	int rc;
	rc=errlog_open(NULL,mode,magic,hdl);
	if (rc==0)
	{
		printf("\nopen errlog sucessful!\n");
	}
	else
	{
		printf("\nopen errlog failed!\n");
	}
	
	extern int begintime, endtime;
	errlog_match_t beginstamp, endstamp, andstamp;
	errlog_match_t hardclass, softclass, orclass;
	errlog_match_t andtop;
	errlog_match_t *p=&andtop;
	int ret;
	errlog_entry_t result;
	
	/* * Select begin and end times */
	
	beginstamp.em_op = LE_OP_GT; /* Expression 0„30…4A0„30…4 */
	beginstamp.em_field = LE_MATCH_TIMESTAMP;
	beginstamp.em_intvalue=begintime;
	endstamp.em_op = LE_OP_LT; /* Expression 0„30…4B0„30…4 */
	endstamp.em_field = LE_MATCH_TIMESTAMP;
	endstamp.em_intvalue=endtime;
	andstamp.em_op = LE_OP_AND; /* 0„30…4A0„30…4 and 0„30…4B0„30…4 */
	andstamp.em_left = &beginstamp;
	andstamp.em_right = &endstamp; /* * Select the classes we0„30…4re interested in. */
	hardclass.em_op = LE_OP_EQUAL; /* Expression 0„30…4C0„30…4 */
	hardclass.em_field = LE_MATCH_CLASS;
	hardclass.em_strvalue = "H";
	softclass.em_op = LE_OP_EQUAL; /* Expression 0„30…4D0„30…4 */
	softclass.em_field = LE_MATCH_CLASS;
	softclass.em_strvalue = "S";
	orclass.em_op = LE_OP_OR; /* 0„30…4C0„30…4 or 0„30…4D0„30…4 */
	
	orclass.em_left = &hardclass;
	orclass.em_right = &softclass;
	andtop.em_op = LE_OP_AND; /* (0„30…4A0„30…4 and 0„30…4B0„30…4;) and (0„30…4C0„30…4 or 0„30…4D0„30…4;) */
	andtop.em_left = &andstamp;
	andtop.em_right = &orclass;
	
	int direction=LE_REVERSE;
	rc=errlog_set_direction(hdl, direction);
	if (rc==0)
	{
		printf("\ndirection errlog sucessful!\n");
	}
	else
	{
		printf("\ndirection errlog failed!\n");
	}
	
	ret = errlog_find_first(hdl,&andtop,&result);
	
	if (ret==0)
	{
		printf("\nfind errlog sucessful!\n");
	}
	else
	{
		printf("\nfind errlog failed!\n");
	}
	
	if (LE_ERR_INVARG == ret)
		printf("\n\n return LE_ERR_INVARG \n");
	
	if (LE_ERR_NOMEM == ret)
		printf("\n\n return LE_ERR_NOMEM \n");
	if (LE_ERR_IO == ret)
		printf("\n\n return LE_ERR_IO \n");
	if (LE_ERR_DONE == ret)
		printf("\n\n return LE_ERR_INVFILE \n");
	
}

------------------------------------------------------------------------------
execute result0„50†2
root@zhguowen_sv:/asmdev/asm#xlc errlog_find.c /usr/lib/liberrlog.a

root@zhguowen_sv:/asmdev/asm#./a.out
open errlog sucessful!
direction errlog sucessful!
find errlog failed!
return LE_ERR_IO

root@zhguowen_sv:/asmdev/asm#
-------------------------------------------------------------------------------------


Problem:

errlog_open,errlog_directory and errlog_find_first subroutine come from the book of Technical Reference: Base Operating System and Extensions, Volume 1.

1.Return error code:LE_ERR_IO, means An i/o error occurred. How to solve this question?
2.Are there any other book to explain errlog subroutine? It has too little infomation in Technical Reference: Base Operating System and Extensions, Volume 1.
3.My mail address:zhguowen0103@hotmail.com

Thanks alot!