Hello, KSB!
I am sorry to hear that you have felt ignored. It's definitely not a fun feeling and is something that I can relate to as well! However, as Phishindude stated, it is possible that those in-game were probably busy with their missions and missed the text in chat, or might have even been AFK at the time (yes, it does happen) when you were trying to get their attention. I wouldn't take it personally as I'm sure it's not meant to be anything against you :)
When I am in-game I always make it a point to greet new fleeties when they say "Hello" or something like it in fleet chat! Hopefully this post will encourage others to do so as well :)