mulltipe data - one graph/adding values to a total
 

What i have to do is draw a graph showing the amount of errors over
time. I have to seperate them into all, answered(which is part of all), any
solved(part of answered). and i can't figure out a way to do it.
Additionally they are supposed to add up: eg if i was to monitor the errors
per month over one year and i had 10 errors each month i dont want a straigt
line at 10, but i want a slope up to a 120 at the end of the year. reason i
cant use the add function in the pivot chart is, that i have to se the count
function already to get the amount of errors during the corresponding month.
Any help would be appreciated