Why do people do this

So with being socially awkward, I try to find the perfect moment to go up to one of the managers at work to sign me in on a device I need to use to do my job. Tell me how as soon as this one particular manager sees me he immediately puts his attention to something else (walks away in a different direction) acting as if he just didn’t see me going toward him. Why do people do this?! It is so irritating and it has not been only him. I’ve had it done by others too. Is it because of my awkwardness? Well it totally makes me feel like a big fool. Especially when I’m already pushing myself to interact.