I agree with mother of faith, each child is different. I have been teaching my niece to read, we started when she was just over a year old, and now she is 4. She has gone through phases, sometimes showing more interest than other times. When she goes through a period of not being interested in flash-cards, books, or anything to do with reading, I just give it a rest for a little while so it doesn't become a 'chore' for her, because kids learn best when it's fun for them.
Recently I discovered a cute website
http://www.starfall.com/ which has helped add variety to her reading exercises. She also enjoys Little Reader, and though she rarely says the words out loud, I know that she can recognize most of the words. She still doesn't want to read from books, but as linzy posted earlier, sometimes our kids can do more than we give them credit for.
We also created a sort of *lotto game* with the words she knows, so she doesn't have to say them out loud (which she often doesn't like to do), but when she hears the word read aloud, she can put the card on the right place on her game board.
*we used card paper made 3 game boards, 9 words per board, each word on its own square. Then we cut out smaller cards with the same words on them. I say "does anyone have the word 'play' on their game board?" if so, then the card is placed on the appropriate square.
This way I can see which words she knows better when she's not in the mood for saying them aloud. From time to time I change the words in the game, taking away old ones and adding a new 'game board' with words from LR, or other flash cards.