excel array formula if result depends on row?

It seems that the result of my array formula depends on the row. Please see the image attached. Cell C2 looks up from the value of the cell above it ("s3") from $A$3:$A$11, and tries to return values in $B$3:$B$11 if matched. So are cells D3,E4,F5, etc. I expect the values should be the same. However, I got "Error in Value" for C2, D3, and E4, as well as M12 and N13. I got FALSE in F5, H7, I8, J9, and L11. The only 2 cells that got valid results are G6 and K10 where the cells themselves are on the same row as where "s3" is found.

I am really puzzled by the result. Could someone please help?

Thanks a lot! Lu

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