Berkeley DB Family

This is my test program:

#include <sys/types.h>
#include <ioLib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <db.h>
#include <db_config.h>
#include <db_int.h>


int create(void)

{

int ret = 0;
int index;
DB *dbp;
DBC *dbcp;
DBT key, data;

char *database;

database = "host:/DB/rule.db";

if ((ret = db_create(&dbp, NULL, 0)) != 0) {
fprintf(stderr, "db_create: %s\n", db_strerror(ret));
exit (1);
}
if ((ret = dbp->set_pagesize(dbp, 1024)) != 0) {
dbp->err(dbp, ret, "set_pagesize");
return 1;
}
if ((ret = dbp->set_cachesize(dbp, 0, 32 * 1024, 0)) != 0) {
dbp->err(dbp, ret, "set_cachesize");
return 1;
}
if ((ret = dbp->open(dbp,NULL,database,NULL, DB_BTREE, DB_CREATE,
0664))!=0) {
dbp->err(dbp, ret, "%s:open", database);
return 1;
/*exit(1);*/
}
retrun 0;

}

when I run it under the simulator(VxSime) of Tornado2.2，it comes the error
information:

host:/DB/rule.db:open: errno = 0xb

but I could see the _db.rule.db in the directorty,

This question puzzled me for a long time.
Looking forward to your help.
thanks a lot!