Panorama test

So I am almost 13 weeks pregnant with twins I have had the blood work done twice to find out the gender and both times it comes back as not a enough DNA Or they cannot tell me if either one has down Syndrome I am kind of scared to why the bloodwork did not work both times but I have a appointment on Friday and they’re going to do my 12 week ultrasound has anyone had this problem we’re both times they did not get a enough information And everything still be ok