ok.. i solved that problem also..
by setting the values as
"".WA_RandomPassword(10, true, true, true, "").""
So now the values get carried forward & everything..
Now when i click checkout, it takes to me EXTERNAL link, to pay the money there.. its not a payment gateway.. but then once after the payment is done the product doesnt get added to DOWNLOAD CENTRE.. niether to my db..
PLEASE HELP.