Excel chart error from 2003 version to 2007

[naveen madhava]

Dear folks,
I have an application which was built on excel 2003 version. However, we have upgraded our office version to 2007 recently. This application has few charts which are constantly throwing errors upon accessing. I have no clue about what fix should be given for this.
Following are the errors shown:

1) "The specified dimension is not valid for the current chart type"

The above error is shown for the code line:
ActiveSheet.ChartObjects("Chart" & Trim(CStr(p_ChartNumber))).Activate

2) There is a list box in the application, while swapping the options in the list following error is shown:
"Requested shapes are locked for selection"

The line in the code where the above exception occurs is :
ActiveSheet.ChartObjects("ChartSingle").Activate


Please, can anybody help me fix this issue?

Thanks in advance,
Naveen M