Excel 2007 : SUMIFS with criteria/sum ranges in a cell drop-down

I've been scouring every Excel forum I can find for what I believe is a relatively simple problem, but still can't find the solution...

Here's the outline:

I want to use two dropdown cells as references for the criteria in the SUMIFS function. For the criteria, this is simple since it is just numeric. But for the criteria range and sum range, I am trying to reference a cell containing a data-validated drop-down list of the named ranges in the sheet. So far, I have gotten to this functioning formula:

=SUMIFS(INDEX(Salad,,2),INDEX(Salad,,1),">="&B4)

where "Salad" is one named range. What I want to be able to do is refer to a cell that contains a drop-down list with all the other named ranges (Salad1, Salad2, Salad3) in it but Excel keeps giving me a #REF! error.

Thanks!