Get record by recno

Question

I want to get record by record number using cursor. I use btree, which is configured to support recno (pdb->set_flags(DB_RECNUM);
I found how to get recno by record and it work:
unsigned int Recno()
  db_recno_t recno;
  Dbt numValue;
  memset(&numValue, 0, sizeof(numValue));
  numValue.set_data(&recno);
  numValue.set_ulen(sizeof(recno));
  numValue.set_flags(DB_DBT_USERMEM);
  //int ret = bdbCursor->c_get(bdbCursor, Key, &data, DB_GET_RECNO)) != 0
  bdbCursor->get(&Key, &numValue, DB_GET_RECNO);
  return (unsigned int)recno;
I trying to do same to get record by recno, but BD just crached and no show error message.
bool MoveToRecno(db_recno_t recno)
  memset(&Key, 0, sizeof(Key));
  Key.set_data(&recno);
  Key.set_size(sizeof(recno));
  Key.set_flags(DB_DBT_USERMEM);
  int ret = bdbCursor->get(&Key, &Value, DB_SET_RECNO);  //program crached here
  return ret == 0;

Answer 1

Found bug: answer will be written to usermem:
  unsigned char * buff = new unsigned char[100];
  memset(&Key, 0, sizeof(Key));
  memcpy(buff, &recno, sizeof(recno));
  Key.set_data(&buff);
  Key.set_ulen(100);
  Key.set_size(sizeof(db_recno_t));
  Key.set_flags(DB_DBT_USERMEM);
  int ret = bdbCursor->get(&Key, &Value, DB_SET_RECNO);