If you select the Chart and select the Blue Columns you will notice that the formula bar now shows:
=SERIES(,'Copy of Sales Response Utilization 2 11 14.xlsx'!Chart_X_Axis,'Copy of Sales Response Utilization 2 11 14.xlsx'!Chart_Series,1)
This is saying that the series is charting the X Axis using a Named Formula called Chart_X_Axis and a Y Axis using Chart_Series
You can check these out in the Name Manager (Formula, Name Manager Tab)
You enter these in the Chart by Right click on the Columns and Select Data, Edit command
When entering the Named Formula you must include the sheet name
eg:
Use: ='Fineline graphs'!Chart_Series
Not: =Chart_Series
Excel will convert it to 'Copy of Sales Response Utilization 2 11 14.xlsx'!Chart_Series
But don't worry about that