How to use MRP_ATP_PUB.Call_ATP with bulk collect

Hi

i want to send ATP Requested_Date_Quantity via an interface to a third party application from EBS R12, for all the products that would be orderable on that application.  But when i select the inventory items using bulk collect and then use the API to get the requested date quantity, it only returns a number for those records up to the bulk collect limit i stipulate, above that number the result is a null. I have created a cut down example of the code to look at this problem (see below). Any help with this would be very much appreciated, and