Thanks for the response.

I'm still getting the invalid currency error.

The store is now switched over to live mode (per cybersource support's recommendation). I have the module configured for "production" and the merchant account set to 'live'. I have the merchant server set to the production / live orderpage:
$this->form_action_url = 'https://orderpage.ic3.com/hop/ProcessOrder.do';

Is there something within zencart that needs to be updated to stop this currency error?

currency
X

X

X

INVALID
usd

Any suggestions appreciated!