Some chart types cannot be combined with other chart types

Good morning,

I am working on a MacBook Air (purchased Oct 2009) running Lion. While working in Excel 2011, I encounter the error "Some chart types cannot be combined with other chart types. Please select a different chart type." I am highlighting 46 cells to create a marked line graph. There are no other charts in the file. I called Microsoft support who told me they had not heard of this problem in Excel (only in PowerPoint). I also took it to an Apple Store Genius, who was unable to solve the problem, which is understandable, given that he does not work for Microsoft.

To try to resolve this issue, I have recopied the data to a new spreadsheet, re-typed all the data to a new spreadsheet, and deleted plist files. When I sent it to a different computer (which was running Excel 2011 and Snow Leopard), I could make the figure but I cannot edit the figure or add data on my laptop.

Any suggestions that you have would be much appreciated,

Signed,

One stressed out PhD student who desperately needs Excel to work