Can somebody please help...I really could use some help?

There's this guy at work. We stare at each other. He mostly stares from afar and when I have one back on him. Only once I cached him staring at me and when I looked at him, he looked away. He never starts conversations or calls (we both have each other phone numbers), he's shy, but only around me, as he has two female co workers he always hangs out with and seems OK around them and even laughs loud when I'm around. I always try to start something by askig how is he, he replies shortly but doesn't want to go. It's like he wants to say something else, but hasn't guts. I also then turn away and walk as I always through a ball in his court by starting the conversation, but he never asks me any question (just the same as I asked him about How are you doing?) or compliment, or flirt or anything that might point he likes me. Once we had an eye lock, we say Hi un smile while p each other, but that's about it. Should I forget about him and try to move on or continue to open up him? It looks like he is not ready to date or have a relationship. Oh, and once he kinda did ask me out (it was at the very beggining when I slipped him my phone number and he took up all his guts to call me very late that day), but then after few days he said "We'll keep in touch". What do you think?