I created a simple test code in arm linux. and It always said "Invalid argument". Do I miss something? thanks!

code:
#include <db_cxx.h>
#include <iostream>
using namespace std;
int main(int argc, char* argv[])
{
DbEnv* envp = NULL;
u_int32_t flags;
try{
flags = DB_CREATE | DB_INIT_MPOOL;
envp = new DbEnv(0);
envp->open("/database", flags, 0 );
} catch(DbException &e){
cerr<<e.what()<<endl;
return -1;
}
return 0;
}