Ok. So im working at Walmart, and whenever a girl passes by me I look at her and give her a smile. But they never smile back. They just kinda look at me then casually look away. What am I doing wrong? And what do you guys think I should do differently? Thanks in advance.

Could be many reasons:

-You could look creepy
-They might have low confidence and aren't use to guys smiling like that
-You're not doing it confidently

Personally I think smiling as you walk passed is weird. I did it for a week and it was just weird. I couldn't get used to it. I felt needy.

I'm not saying follow the crowd but I haven't seen many guys smiling at women walking passed. At the maximum, it could be eye contact or a sexy look but don't go searching for women to make eye contact with or to smile at, let it happen naturally otherwise it's quite needy. When you're walking through the mall you're focussed on the women when your focus should be your life, where you're going, what you're doing etc.

titanman pretty much covered it. Although, when I'm at work and I smile at girls they usually smile back. Sometimes though, they're in a rush trying to find something and they just look at you for a second, and it doesn't register in their brains that you smiled at them since they're in a rush. Try being more proactive and saying something to them like "Can I help you?" Be friendly, not creepy. It won't seem like you're hitting on them either cause you work there and are supposed to be helping them.

I disagree with everything the two guys above said. It's not weird at all to smile at people in the street. You know why they don't return your smile back? Because you're not genuine. You're simply smiling to force a reaction out of them... not because you feel the desire to smile. You want to get something from them (a smile back, approach invitation or whatever). Women sense when there's an in-congruence in your words, thoughts and actions. Your smile is fake, you're only smiling to see what will happen next (what's her response); therefore, you're actions are not expressing how you feel in your body. Women then see that you're smile is just fake and approval seeking; they don't smile back. Simple as that.

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Greatness is never borned

Now this is some advice I'd listen to.

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Been around the world twice, Talked to everyone once...

I agree. That's pretty much what I said.

In my post:

"don't go searching for women to make eye contact with or to smile at, let it happen naturally "

Again, I disagree with you. You just said to not search for women to smile at you. Yes you can. It is simply a matter of directing your focus on what you want to do, not on the response. Even let's say if deep down inside you don't want to smile, yet you're able to focus your attention on smiling to be genuine and not needy, you will get good responses from girls. You're basically saying that if it doesn't happen naturally, it's needy; which is not true at all and I've done this many times (not with smiling, but with more difficult tasks). It's needy because YOU give it that interpretation. In your own reality, you define it as needy, therefore other girls will think it's needy. But if you're able to focus and detach yourself from the outcome, you can be genuinely non - needy and have amazing responses from any girl you want.
When you want to attract a woman, you don't focus on where you're going or if you're eating a sandwitch. You focus on getting to know the girl and removing yourself from any possible feelings of neediness. You approach with a feeling of desire. Focusing on where you're walking or what you're doing is not going to make a difference in being needy at all. You'll simply look pre-occupied

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Greatness is never borned

We'll agree to disagree on the smiling thing.

I agree one your last point though, I obviously made that point badly in my post. But I just don't see the need to go about looking like the cheshire cat at girls.

i get 4/10 positive responses when i smile at women. if you take a social dancing class and go social dancing, social dancing is a flirt fest so you can learn to smile/flirt that way. but, my technique is #1 Wait. Make yourself mentally ready to let the woman go and not smile at her. #2. Look at her face/eyes #3 Smile #4 Plant your feet or keep walking like you were walking or doing whatever you were doing. This communicates it was just a smile, that is all, no further interaction forced on the girl. #5 Look away. You can look my post history as I talk about my technique in more detail in previous posts. I am a newbie and have not dated, but I get some smiles back..