Excel Help - Student Attendance

Thank you so much for your time and trying to help me out. Once I get a working sheet, it will save me many, many hours a week. Unfortunately the roster is very fluid, as students get added and withdrawn many times per week & we teachers don't know we are getting new kids till they pop up in our roster their first day. Online schools are very different with this than traditional schools. Over the year I probably have 500  kids total come in and out. Only about 100 will be the same all year. 

I downloaded the sheet you made, but as soon as I paste new data below the old data, all numbers in the report have dashes. I have been using excel a long time, but only do very simple things, so am not extremely well versed. Poll # change each day - not sure if that matters. Some days we will have 1 or 2, others 4-7. Here are 3 things I tried & I'm not sure what I am doing wrong.  I played around with it a bit more before making the video and cannot figure it out.   https://somup.com/c0QhD3Akve