Please help. Can I use a date as the LOOKUP value in HLOOKUP?

I have a spreadsheet that has cell D1 set up to "TODAY"

In a different table {2 Week Resource Plan}, There are a set of values under each day ie Induct, Pack, {Row 3}

=HLOOKUP(INPUT!D1,'[2 Week Resource Plan 20.08.2013.xlsx]Resource'!$FY$1:$GC$11,3,FALSE)

When I do it with a value it works, (as above) but when I do it with a date it doesn't work. I tried to do it by copying D1 into Cell D2, but formatted as a value but it won't let me, because B2 References A2!

Can anyone help?