My Apple Watch does not show upcoming events when i look at the calendar in the watch. What could be wrong?

First, make sure that the calendar on Apple Watch is set to mirror your iPhone, Watch → Calendar → Mirror my iPhone.

If your calendar is set to mirror your iPhone but you are still not seeing upcoming events on your watch, I would go ahead and re-sync the calendar data, Watch → General → Reset → Reset Sync Data.

Hope that helps!