undefined symbol Iter_Single

I'm trying to use y_iterate for Vehicles. So what I did was:

new Iterator:Vehicles[MAX_VEHICLES];

Then when adding the vehicle

Iter_Add(Vehicles, gameid);

i get these errors

error 017: undefined symbol "Iter_Single@Vehicles"
error 017: undefined symbol "Iterator@Vehicles"

at the Iter_Add line

how do I fix it? Weird