I became a Buddhist because I want to be happy. Why do I still have suffering?

...while all beings want happiness, what we get is suffering. The reason why we don't get what we want, and why we get what we don't want, is because our wishes and our actions are contradictory to one another."

"While we wish for happiness, we do not engage in virtuous actions, the causes of happiness. While we wish not to suffer, we do engage in non-virtuous actions that are causes of suffering. Therefore, we are reborn in the three lower realms and suffer terribly there. So we need to understand and fear the intense and prolonged suffering of lower rebirth."

His Holiness, 17th Gyalwang Karmapa
Ogyen Trinley Dorje

From teaching on Torch of Certainty and commentary by Jamgon Lodro Thaye 

at 31st Kagyu Monlam