OFFSET for chart that has varying X and Y ranges

[rugbyhubby]

I'm working on a chart that would display two data series (this is for tracking bloodwork results). The data is in a flat file and I want the user to enter a start/end date for the chart but they don't have to remember which date they had the blood work done. I have a formula that will find the closest date to the start and end date entered. I have another formula that will count the number of rows of data between those dates. The user then chooses which datapoints to compare via a drop down. With the dropdown I know the column for the data as well as the hi and low range for that data point. I am then displaying the data with a simple index formula. Since the data points could range from 5 to 100 I want to use OFFSET to create the chart. I'm using an OFFSET formula but I can't get the COUNTA portion of the formula to work of a referenced range. I hope I'm providing all the details and I will try to attach a clean spreadsheet as well.

Using =ADDRESS(27,6)&":"&ADDRESS((27+($E$7-1)),6) I can get the range $F$27:$F$31 using the starting point and the number of 'rows' of data that exist. However, when I create my OFFSET formula for the chart using the formula above embedded in the COUNTA argument the COUNTA argument evaluates the "formula" and not the range.

Here's my offset formula (there are three: dates, datapoint1, datapoint2):
=OFFSET(DP!$E$26,1,1,COUNTA(ADDRESS(26,6)&":"&ADDRESS((26+DP!$E$7),6)),1)
this is saved as a named range.

The data looks like this.
Platelet Count Hemoglobin
3/2/2012 207 14.1
4/2/2012 182 14.3
5/2/2012 193 15.2
6/2/2012 161 14.6
7/2/2012 15 150

If I chose a longer range then there would be more rows of data and I want the chart to automatically account for that.

Please tell me if you need anything further.

Thanks...bill

[rugbyhubby]

Does anyone have any thoughts on this one? I see people have viewed but usually I get a quick response (even if I'm trying to do something that isn't possible!)