order step 2->3 session variable info required

This is my bug but I need a pointer.

I have set COD as a shipping option, as it implies extra complicated costs, calculated by Advanced Shipper.

When selected, only the COD payment option is offered on the payment page as default: I disable the other methods if COD has been selected.

This has worked fine during my testing a long time again but now I have found that when passing from step 2 to 3 Payment Information, I get an error message “Please select a payment method for your order.” If I refresh the page the error clears and I can proceed with the order.

Can someone tell me what variable is not set at this point/what triggers this error message so I can track it?

Thanks
Steve

I recently had a problem with Advanced Shipper and Fast & Easy Checkout working together..........if you do have FEC installed, you might disable it and try checking out again.

if you do have FEC installed, you might disable it and try checking out again.

No I don't have any checkout mods. I don't think Advanced Shipper is the problem, it'll be my hacks... it usually is.

Well, I'm stuck.

This is what I have done:

1. when someone selects a cod shipping option, I check for this in
   includes\modules\pages\checkout_payment\header_php.php
   and set

$cod_shipping=true2) in all the payment modules I disable them like this:

I add the variable in the class constructor:

// class constructor
function moneyorder() {
global $order,$cod_shipping;and then

if (IS_ADMIN_FLAG === false && $cod_shipping==TRUE)
{$this->enabled = false;}Both of which work ok.

3. in COD I have

if (IS_ADMIN_FLAG === false && $cod_shipping != TRUE)
{$this->enabled = false;}So, when I get to step 2 of 3, only the cod option is shown.

Attached is a screenshot at this point showing relevant variables.
I try to proceed and it bounces me back with the error message "Please select a payment method for your order." - also attached.

From what I can see, the conditions of the error message are not met.

if ( ($_SESSION['payment'] == '' || !is_object($$_SESSION['payment']) ) && $credit_covers === FALSE) {
$messageStack->add_session('checkout_payment', ERROR_NO_PAYMENT_MODULE_SELECTED, 'error');So what else do I need to look at?

Can the knowledgeables perhaps comment that this simple approach seems ok or that there is a different method I should take?