Excel 2007 : dragging a line in a chart

I've recently started evaluating Excel 2007. I have several old chromatography applications written in Excel 2000/2003. One of the first things I've discovered was that my baseline routines are broken. In previous versions you could setup a line (front x/y, rear x/y points) in a block of four cells. Then you could add this as a series on an xy-scatter chart. Clicking on the line, the end points would show a filled symbol and when you hovered over the point, the drag-drop cursor would appear. You could then click on the point and drag it around the chart, moving in one dimension at a time, and the data in the cells would be updated accordingly. Simple but it worked.

In Excel 2007, the end points appear, if I try to drag them nothing happens, the drag-drop cursor (4-sided arrow) appears when I move away from the line, but this is related to the plot area of the chart.

Any ideas?

Thanks,

rb