Here the part of my code that isn't really working:

mob/Shopguy
Talk(mob/M as mob)
var/list/sale = list("Thing1","Thing2","Nothing")
var/buy = input("What do you want to buy?","Hello","Thing1")in sale
var/thing_chosen
switch(buy)
if("Thing1") thing_chosen = new /obj/thing1
if("Thing2") thing_chosen = new /obj/thing2
if("Nothing")
usr << "Later, then"
return
thing_chosen.Move(usr)
usr << "Thanks for coming!"

There it is. The problem is the Move proc, it says:
error:thing_chosen.Move:bad proc

I really don't know whats wrong here, and I've tried a lot.
If I try to take out the thing_chosen.Move(usr) so it becomes Move(usr), it only moves the shopguy to you inventory.
Please give me an idea of how to correct this. Thanks!