Gender Determination Ultrasound ?

Has anyone gone to have a 3D/4D ultrasound to determine the gender and the tech wasn’t able to tell the gender? I’m 15w1d and am going today. I’m hoping they are able to tell. I have my gender reveal party Sunday. And I really don’t want to have to cancel it. I was hoping to have my sneak peek results too but my first sample was declined and I haven’t received a confirmation email that they received my second sample yet. Just wanted to know everyone’s experiences so far, thanks!