formula returning false

hi guys
i have a problem with a formula i am using
[CODE]=IF('working sheet'!D22<>"",'working sheet'!D22&IF('working sheet'!D24<>""," or "&'working sheet'!D24,""))[/CODE

what should happen is this

if there is a number in d22 and d24 the formula works fine
if there is no number in d22 then the formula doesnt work and returns the answer false

can anyone helps please