I dont think you have to convert 10g chart report into 11g Pivot chat,you can use normal chart in 11g as well plz check the Chart options carefully which column is palced in vertical,Horizantal and line sections..
If you edit your chart, check the columns in "Layout > Line-Bar Graph > Bar and Lines > Group by section" you'll see most of your columns here. you'll have to either remove unnecessary columns from criteria tab or drag them in "Excluded" section.
If you pull more than necessary columns in criteria, the analysis result will be shown as per the logic attached to all these columns. Try to keep only columns that are necessary for final output.