Auth.net SIM Error 99 Cannot be accepted

[RixStix]

1. for the "99" error message, do: http://www.zen-cart.com/showthread.p..._currency_code

2. For Authorize.net setup instructions:
AIM: http://www.zen-cart.com/content.php?...payment-module
SIM: http://www.zen-cart.com/content.php?...payment-module

I've never had any difficulty switching between modules. Nothing special to do beyond what's listed in both of those articles.

Those are the instructions in my hands and both suggestions for use of the currency code have been tested independent of each other. Both currency code edits get past the first Hash error,

AIM is fully functional on our live site. SIM is being tested (unsuccessfully) on our sandbox site.

the error that exists now is the

Your script timed out while we were trying to post transaction results to it.
Transaction ID: 0

We would consider PayPal only for credit card processing instead of SIM except PayPal requires a PayPal account to process a credit card and there are quite a few customers that refuse to create a PayPal account.