Offset function not capturing entire range

I will be making a chart with the date on the x-axis. I want to make sure that as more dates get added to the data set that the chart will automatically update and populate those dates. I also want to be able to type, for example, =COUNTA(F_MS30) instead of =COUNTA(A:A) with +F_MS30" being the name of the range of cells.

Thanks for your help but it's not working. It shows no cells selected when I tested it.