Problem regarding to an alternative shipping method for FreeShipping items

[Ashely]

Hi there,

I created a new shipping module for freeshipping items (those with "product_is_always_free_shipping" == 1) to add an option to "Upgrade to Express Post". Everything works just fine when customers use Shipping Estimator or go to the first step of check out to choose the shipping method. However, when they choose the "Upgrade to Express" option and move on to the checkout payment page, the shipping method reverses to the normal Free Shipping and the shipping cost goes back to "0". So seemingly the order total module couldn't recognise the new shipping method.

Anyone know the reason? What should I do now? Is there any other file (e.g., function file, etc.) that I must revise first as well? I created a couple of shipping modules myself before but never encountered this problem before...

Any suggestions or advices would be really very appreciated!
Thanks in advance.

Ashely

[Ashely]

Does anyone have any idea?