beginner question - having a problem showing graphs lines with data entered in impress and presentation mode

Using LibreOffice Impress presentation to show graphs- I added columns and rows correctly - entered the data but no dots or lines appeared- this is the first entry in each of 6 columns do I need 2 sets of information to see the line or should the data points show up when only one set of data? Thanks Denise

Can you please add an example table to replicate this?