One challenge of teaching well is that you can't always make every student happy.
It's the same with parenting. There are times when one child or another is unhappy. They may need more or different.
The same is true in the classroom.
You want all students to be happy, engaged, and invested, and you work towards that aim every day as you choreograph the day, the lessons, and events. Yet, at one time or another someone raises their head or hand in unhappiness, they want more or different.
That's the signal to rethink the plan--what can you change to enlist that child's energy and positivity? What is leading to the discontent?
As I often say, teaching well is a limitless proposition, and each day you bring the best of what you can do, respect for every child and colleague, and the knowledge that every day can't be the best day, instead some days are the challenging days that lead to "best days" later on.