Mixed signals

I have a bit of a situation on my hands. I've been told from three people that a man I work with is interested in me. However, when I get the opportunity to see him and interact with him, I don't see what they're saying. For example, I went on lunch today and we saw each other walking down the street. I looked him right in the eye and said "Hi, how are you?" With a smile. All he said was "Hi...." Hardly looking at me and kept walking. When he's in the building fixing things, I know he's very focused on work. I'm the same way. When I'm in the middle of something, I can't be distracted. I've been into him and never told anyone until I found out that he's supposedly into me. I'm starting to doubt it. I trust the two who told me but he acts like he wants me to drop dead. The one person that told me I hardly know. I'm not implying that they're not trustworthy. I hardly know them. I'm not the poster child for talking to men. I feel like I've gotten in over my head with this and let myself down. A few times both of us caught each other looking back at each other but that doesn't mean a thing. I admire his intelligence and am highly attracted to him. He has a sense of humor which attracts me even more. Maybe I'm just meant to be almost 30 and single forever. ☹️ I wish I never let this consume me and just laughed at it. I feel like an idiot.