=(SUMPRODUCT(--('Cattle Mvts'!$E$29:'Cattle Mvts'!$E$41='Cattle
Budget'!D7),('Cattle Mvts'!$C$29:'Cattle Mvts'!$C$41)*'Feedlot
Assumptions'!$B$3))

The existing formula basically says if date at D7 equals a date in the array
E29 to E41 then multiply the corresponding figure in array C29 to C41 by B3.
i now need to expand it to include the concept to do that if the contents of
array B29 to B41 equal the contents of either A9 or A18, otherwise leave
blank.

Hope someone can help

Anthony