Combine 2 named-ranges for a single series line chart

Hi,

In the attached WB -

Sheet A has a 3 cells (A1:A3) named range: AA
Sheet B has a 7 cells (A11:A17) named range: BB

In sheet C I would like to plot a 'Line' chart from a Single Series - the combination of AA+BB

What I have in mind is that the single series source should be:
2, 3, 1, 7, 5, 9, 8, 4, 6, 10

In the series source I've tried to type:

=Book18.xls!AA, Book18.xls!BB
or:
='Book18.xls'!AA, 'Book18.xls'!BB

Excel excepts only: =Book18.xls!AA OR =Book18.xls!BB but no both

Any assistance will be appreciated,

Elm