You will feel awkward if the other person will not say anything after a greetings, or to make it worst, when they do not notice you despite making a scene. It happens to me all the time that is why I became introvert. There are people that don't notice you despite being friendly. I feel some insecure there or they will just choose the people that they will know or be friends with. I can be too quiet and I can be too talkative. It depends on the response of the people around me. Sometimes, when I said something and the people around me will just look at me and nod, I will not continue. This surely stops me from initiating to tell something again. Some people do not feel like talking to me when I start a conversation, that is why at present, I wait for someone to start a conversation and I will surely response in a friendly matter. People are people, they choose the people they talk with so I should be like that too.