data validation list formula

[peterhinton]

hi all,

anyone got a formula for my problem

I have numbers in column A, and a status in column B,

I want to be able to have a drop down cell with data validation for a list of numbers that have the status FREE,

I tried an array of {=IF(B:B="Free",A:A)} as the validation rule but this does not work ( yeah this may of sounded basic but was worth a try )

any help would be great, I already have a way using an array and a helper column but would rather not use that if possible,