Kneecap pain doing glute bridges

Hi, 

When doing flute bridges, I feel pain on the lower left side of my kneecap. Anyone else had this problem? I don’t think I’m doing it wrong, very simple exercise. Ideas how to resolve it? 
Thanks!

Martin

Try using glutes/hips more than quads. Sometimes my knees feel weird if I push too much with my quads. Either that or your knees are fucked up, which is what my issue used to be before surgery.