When you meet someone at a business event and exchange business cards, they are NOT automatically part of your network. Many people confuse knowing someone with actually being in each other's network.
In order to really build a business relationship you need to have a series of interactions with people. You need to understand their business and who would be their ideal clients. They need to know the same thing about you.
Too often people meet a new business contact and add them to the database, but do not think about the next steps.
Networking is all in the follow up.
If you happen to have a conversation with someone at a business event, the best thing to do is to follow up a few days later with an email, phone call or handwritten note. This simple gesture is a way to remind the other person of you, and allows you to instigate the next step of having lunch or inviting them to attend another business event.
Keep in mind that to really add someone to your "network of professional contacts" you need to have seven to ten times where you personally interact. Less than that and they are just a person you slightly know. By proactively following up, you will move them into your network at a faster pace.
If you just wait for the other person to follow up with you, you may wait for a long time.
Have A Great Day.