What do you mean when a boy sends me a message and doesn't chat with me?

It may be a habit for boys to send you messages every morning, but never chat with you. Maybe he doesn't know what to talk about.

Boys are introverted:

This happened to an introverted boy. He doesn't know what to talk about, or even how to talk.

There is the possibility of liking you:

This boy likes you, so he asks good morning every day to get your attention. He didn't know what to talk about, because you didn't reply to him after sending a message.

Form a habit:

Once some people form a habit, it is difficult to change it. Maybe even afraid of each other's sadness or something. So now that he is used to it, he is unwilling to change. Because I have met such a person who often gives people praise. I also suggest that you communicate further to ensure that.