Rogue macro

/equipslot 16 Balanced Heartseeker(dagger)
/cast [stealth] Pick Pocket
/cast Backstab
/equipslot 16 Venerable Dal'Rend's Sacred Charge(sword)

It's so annoying when I hit that and the target isn't close enough to get hit, or anything else like that...

Is there a way that I can add a line that will only let it be cast if the target is close enough for it to work? And if there is, what is the line?