Payment gateway plugin development

[sa_mstdss015]

Hello,

I am developing VM plugin for an online payment service provider.

The provider provides an URL to which i need to redirect customer.

When I redirect I need to send few parameters for eg. ID, PASSWORD, TRANSACTION ID


I have done th following steps:

If i click the product details button it will show the ADD to Cart button after clicking on this it will redirect to Checkout page but the following error will come.

The problem is shipment selection.

If I enable the shipment address that time also  "Please select a shipment method" and "We are sorry, no shipment method matches the characteristics of your order."

How to solve this problem in virtuemart.


Thanks,
Raj