Named ranges in charts

I have used named ranges in charts and worked fine. Its been a while and I named some ranges as usually, then when I aselect the chart and try to modify the values by inputting the new name (is range B8:B1000) it wont take it. I know I must just not rememeber how to do it. Got me frustrated.

I tried many things: { and ={" etc.....

how do I type in the name so it works????

HELP