If you mean it's not traded, it's because those project have have no real value, maybe scam and just want to get fiat via ICO. They can't apply for dex exchanges and people don't want to trade it on cex exchanges. Bad projects like those have many sell orders with almost zero values on cex but there are no buy order, no trade made yet. Stay away from them.
Thats just one reason out of a lot. For example have a look at the verity project. Very active with a huge userbase, but their coin isnt traded on common exchanges. The reason is the team wants to focus on developing their product and currently have no interested in trades of the token.