Hi...it's me...Boomer. My experience with people of huge inteligence...like engineers is that those who do not acknowledge your greeting are usually insecure. That means they are not sure that they should respond as then they feel they might have to actually engage in real conversation. My other experiece is that 7 out of 10 engineers do not know how to sociaize...which also makes them insecure...it is a wicked circle. I feel that they spent those early formative years studing into the weeee hrs of the night when people like me were....sipping adult beverages in the local pub. One way to combate this problem?????give em a big hug whan you say hello!....ok...well...maybe not.