Anatomy scan today but couldn't see the sex!!

My baby looks perfect so far but he or she is so stubborn that my little angel moved a lot but wouldn't move from a really bad position to try and see the sex.....butt down on my bladder and wouldn't move from there!!! I tried jumping, wiggling , everything but nothing!! So I'm really disappointed but get to go back soon to try again!! Anyone else ever have that problem not being able to find out the sex at the anatomy scan??