Problem! PP Express only works with "selcted currency" set!

[stevenicel]

Hi all.
I have been at this for two days straight reading every darn post that might have relevant info to try, but no luck yet!. I've done a lotta readin' and tried many suggestions from other related threads.

The situation is this:

My PayPal Express checkout will only work when I have the currency in the module set on "selected currency". AUD is the default currency set in the admin, but the transaction still goes through as USD when it gets to PayPal. If I change this to "only AUD" in the PP Express module settings, the checkout process throws an 10426 error at the 3rd checkout page when it tries to query the Paypal site for payment then goes back to checkout step 1.
I have the default currency in PayPal set to AUD and every currency setting in Zencart set to AUD. But there is also USD and EUR currencies set in admin>currencies.

With my Paypal IPN checkout option, If I set the module currency to "selected currency", the PayPal site automatically receives the shopping cart total correctly BUT in USD (as I said earlier, AUD is the default currency in the admin and is what I want). But if I use "only AUD" in the PayPal module, the checkout takes you to the PayPal payment site but the shoppong cart total is not entered in the PayPal checkout page, It's just left set at $0.

I am using ZC 1.3.7 with the latest PayPal patch applied and I have tried setting the default english.php file setting around line 43 to read: define('LANGUAGE_CURRENCY', 'AUD'); but still no luck.

Can anybody shed some light on this dark computer void?

Steve

Sorry, heading was a bit misleading, so I re-wrote it.