Authorize.net AIM - HASH error after confirming order

[TJB]

I am testing my site, and am receiving the following error after confirming the order with a real credit card #. (There have been a few threads that I have reviewed in the forum, but haven't seen an answer to why this error appears so I apologize for creating another thread)
"WARNING: Security hash problem. Please contact store-owner immediately. Your order has *not* been fully authorized."

The credit card has actually went through and Authorize.net has taken the money out of the account.

I turned on the Debug Mode in the Authorize.net Module and received the log via email. The response text says "This transaction has been approved."
The [HashMatchStatus] => FAIL in the log.

I am using Zen Cart v1.3.8a/v1.3.8

I have confirmed that the cURL settings are correct (Configuration > MY STORE)
cURL Proxy Status: TRUE
cURL Proxy Address: proxy.shr.secureserver.net:3128 (I am using GoDaddy)


MODULES > PAYMENT : Authorize.net (AIM) Module

Enable Authorize.net (AIM) Module: True
Login ID:xxxxxxxxx (removed)
Transaction Key:****************
MD5 Hash:****
Transaction Mode: Production
Authorization Type: Authorize+Capture
Enable Database Storage:True
Customer Notifications:False
Merchant Notifications: True
Request CVV Number: False
Sort order of display: 1
Payment Zone : --none--
Set Completed Order Status: Processing [2]
Set Refunded Order Status: Pending [1]
Debug Mode: Log and Email


I noticed on Authorize.net's site in the following article (http://www.authorize.net/kb.asp?page...sp%3Fkbid%3D74) that the MD5 Hash is not necessary when using AIM. I have tried leaving it blank in the module but it won't work without something put in the field.

[TJB]

I swear I tried this before but I just tried it again it now works without the error. I left the hash field blank and now it works without the "WARNING: Security hash problem. Please contact store-owner immediately. Your order has *not* been fully authorized." appearing ...