loading and unloading by shuttle car

Hello,
I have created a model which demonstrates the operation of shuttle car.
I have here produced 2 item types namely itemtype 1 and item type 2.
item type 1 is generated from souce2 and then provided to queue3. queue is used here for batch processing of size 2.
the output port of queue 3 is connected to queue 6.
similarly itemtype 2 is generated from source1 and source 13
and then supplied to relative queues such as queue 4 and queue 12.
queue 4 and 12 have common output at queue 7.
here ASRSvehicle is used as shuttle car.
here we have used lables for counting itemtype 1 and item type 2.
the capacity is set to 4.
our requirement is it should take 2 numbers of itemtype1 and 2 no. of item type 2 (always)and unload to respective outports.the process is it should take 2 nos. of item type 1 and the it should go to collect 2 nos of itemtype 2 , then it should release itemtype 1
and then item type 2.
it should not take 4 nos of similar itemtype.
if you give any idea instead of ASRSvehicle what will be the better option for shuttle car.

I´m not sure what Version of FlexSim you are using, but what you are looking for is possible by using Tasksequences.
With FlexSim 6 there is a tutorial under help/tutorials for explaining how they work.