Can't change default shipping carrier (PS 1.4.0.17)

[MarkH]

I have been involved with fixing, making enhancements and improving a health food Prestashop based on an owner's list of around 20 requirements. I am fairly new to Prestashop. I have navigated my way around most required changes but this one has defeated me (so far!).

 

I have hit an issue trying to replace a shipping carrier. Whatever I do, the only shipping carrier showing is the old one (see screen below - it is NZ Post). It is based on a module but we wish to code the rates using Prestashop calculations based on weight.

 

This has been defined with a new carrier (called "Shipping") but when trying to change the default carrier, only one option shows up and hence can never be changed. Adding a new carrier doesn't seem to add it to any of the dropdown carrier boxes. I even tried to override it by updating PS_CARRIER_DEFAULT in the database but that hasn't altered anything either. I also note that the carrier id changes after every edit (maybe this is correct?). I have included a screen below with the dropdown box opened showing only one option. What can I do to change my carrier over to a new one. I really want to keep the existing one and add a new one which will become the default and main option.

 

If it is important, PHP level is 5.2.17 and MySQL is 5.5.23-55 and PS is 1.4.0.17..

 

Any other screen shots or info required?

 

What do you suggest I do? It "feels" like a Prestashop "bug" but it may be something that I am doing wrong.