stacked line chart - not column

Hi,

I'm looking for a graph that corresponds to Excel's stacked line chart, where I have one data line from one table, and one from another (with different scales).

What I'd like to achive is something like this:

(The SPD values are found in one table, and POLQA in another. The tables are structured in the same way.)

I can select value fields from the two tables - but I cannot get the two sets of data visible as two separate graphs (as it's only one Y asis formatting that is available in Formatting).

This seems to work when combining a line chart and bar / column chart, but that is not what I want.

This sounds to me as a rather basic feature, and it's available in excel. Is it me that cannot find it?

Thanks in advance for any assistance!

//Eva-Lotta