Help needed with WTD and MTD in crosstab!

[actcognosuser]

Hi all,
I am facing two issues.   

1) I calculated weekly sum  by pulling in
total for date column(i.e for 1 ,2 and 3rd).But the percentage(simple interest) values seem to be off.It is adding up all the percentages for the week which is incorrect.What I need is sum of selling price for all days/sum of cost price for all days.

In crosstab cell properties , I used define content as yes and dragged in simple interest value and changed the aggregation property.I either get a total of percentages or a blank cell.How do i get the right percentage?
                                   
                                   |1/1/09 | 2/1/09|3/1/09 | Week|4/1/09 |Week|
|------------------------|----------------------------------------------
Cost price                     |
Selling price                   |
Principal                        |
Simple Interest(%)          |

2)The second issue is I need a month to date value.i.e sum up the weekly values in the crosstab.If a do a total(week).It did not work.
Also I dont want the percentages to be summed up like for the weekly one.
Please advise!