Data in Subform

Hi guys,

I have a subform where i can "add new records" and fetch records from a form to my subform.

The first row fetches the record perfectly, but from the second row...it fetches nothing.

This is my fetching script:

for each rec in Available [ID == input.Product.Model]
{
    input.Product.Supplierl = rec.Supplier_Available;
    input.Product.Date = rec.Date_Available;
    input.Product.Price = rec.Price_Available;
    input.Product.Stock = rec.Price_Stock available;
}

THis code only fetches data in the first row. But from the second it just leaves it blank.

Is there a script to "subtract de stock? when i click submit?