Help with switching MH with OFH
 

I haven't been playing wow since awhile before 4.0. When I was I used this macro to switch my main hand weapon (sword) with my off hand weapon (dagger) on my rouge. Last night was my first time playing again and this macro didn't work. Well it worked a few times then when I would press it it would put the weapon in my main hand slot as my cursor as if I was picking up an item to move it. So what's up what should I do to achieve my desires now?? Thanks

/script PickupInventoryItem(16); PickupInventoryItem(17);

Not 100% sure, but I think my macro for MH/OH swap is this:
Let me know if this is correct...

-Shxdxws