what's wrong with this formula (for linear Interpolation)

Dear all

what's wrong with this formula, it is supposed to be linear interpolation, type the temperature(x) in C10 to give the factor (y), but it always give REF error.

X values are in A10 to A38
Y values are in B10 to B38

=INDEX($A$10:$B$38,MATCH(C10,$A$10:$A$38,1),2)+
(C10-INDEX($A$10:$B$38,MATCH(C10,$A$10:$A$38,1),1))*
(INDEX($A$10:$B$38, MATCH(C10,$A$10:$A$38,1)+1,2)-
INDEX($A$10:$B$38, MATCH(C10,$A$10:$A$38,1),2))/
(INDEX($A$10:$B$38, MATCH(C10,$A$10:$A$38,1)+1,1)-
INDEX($A$10:$B$38,MATCH(C10,$A$10:$A$38,1),1))


any suggesions please!

thanks for your patience

Where's the formula in the first post, not everyone can download. Also review your thread title

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