Charting Problem - Chart Wizard fails to work properly

I have been charting for years using an older version of Excel. I am now using Excel 2000 and the Wizard is quite different. I am charting mutual fund weekly
year-to-date returns using columns. After acquiring several weeks of data I started to chart.
The charting went okay but then I started adding another series :bench mark year-to-date data so that I can visually compare the two. All went right for the first two charts but on the subsequent charts I was getting strange data charted. I deleted worksheets for all those charts and to make things simple I made a chart of only the first seven data points of mutual fund data, The resulting chart had had only two columns. The first data point was was shown in column seven and data point 7 was now shown as column 1. There were no columns shown for data points 2 through 6. I thought I must have messed up Excel so I re-installed it but no change.
I will sureley appreciate your help!
cranlou

Thanks Mr. Pope,
I think I have narrowed the problem down somewhat. For the first three or four charts no problem. After that I create the chart and it is okay. I then go back to my data sheet and format,unhide the columns that were hidden to draw the chart. Now when I go a look at that chart it now shows several series or data instead of one, even though those data columns were hidden when I constructed the chart.
cranlou