Why don't the black expat men in our city greet back or even look at me when I say them "Aye yo man"? Is it really mean of me to say them that?

As you all know I turned 24 just over 2 weeks ago and I actually live in Bangalore in India but born in West Bengal state of India. As Bangalore is the IT hub of India, many foreigners do come here expats. Like there is this big luxurious mall where expats who are white, black and East Asians do visit. There in the mall I have talked with plenty of expat women who are white and the conversations went good. I saw some black expat men too in the mall 4 days ago and they can be African American or even from some African country so I tried to greet them saying "Aye yo man" but they didn't even notice me. I just try to greet them like its shown in Youtube videos or shows or games like GTA San Andreas or GTA 5 but they didn't even look at me let alone greet back. Why?