1. Check the Cayan/Merchant Warehouse SiteID, Key, and Name you entered into Design Manager.  Make sure they are all entered case-sensitive; the name must be entered exactly how it was given by Cayan/Merchant Warehouse.
2. Make sure that the latest updates and service packs for MS Windows are installed. 
3. Check the browser to make sure that it supports 128-bit Encryption
4. Make sure that Microsoft XML 3.0 or higher is on the machine.  The program file required is msxml3.dll and should reside in the windows/system32 directory.  This version or higher is shipped with all of the latest services packs of Windows XP or higher.  Design Manager SE6/Pro7 does not support any Windows system prior to Windows XP SP2. (Cloud users do not need to worry about this)
5. Make sure that any firewalls are open for:
   • https://ps1.merchantware.net
   • http://merchantwarehouse.com
   • http://cayan.com
   • http://www.w3.org
6. Check the error codes:

APPROVED
FAILED	1001	user authentication failed
DECLINED	1002	invalid transaction
DECLINED	1003	invalid transaction type
DECLINED	1004	invalid amount
DECLINED	1005	invalid merchant info
DECLINED	1007	field format error
FAILED	1008	not a transaction server
DECLINED	1009	invalid parameter stream
DECLINED	1010	too many line items
FAILED	1011	client timeout waiting for response
DECLINED	1012	Normal declined message (i.e. card was really declined)
FAILED	1012	Normal Failed Message (i.e. card really failed)
REFERRAL	1013	Normal, please call.
FAILED	1014	transaction type not supported by version (i.e. maybe your account is not set up to take Amex or other card type)
DECLINED	1019	original transaction id not found
DECLINED	1020	customer ref num not found
DECLINED	1022	invalid aba num
DECLINED	1023	invalid account num
DECLINED	1024	invalid exp date
FAILED	1025	transaction type not supported by host
DECLINED	1026	invalid ref num
DECLINED	1027	invalid receipt info
DECLINED	1028	invalid check holder name
DECLINED	1029	invalid check num
DECLINED	1030	check dl verification requires dl state
FAILED	1040	transaction did not connect
DECLINED	1050	insufficient funds available
FAILED	1099	general error
DECLINED	1100	invalid transaction returned from host
FAILED	1101	invalid timeout value
FAILED	1102	processor not available
FAILED	1103	error reading response
FAILED	1104	timeout waiting for processor
FAILED	1105	credit error
FAILED	1106	host not available
FAILED	1107	duplicate suppression timeout
FAILED	1108	void error
FAILED	1109	timeout waiting for host
DECLINED,DUPLICATE	1110	duplicate transaction
FAILED	1111	capture error
DECLINED	1112	failed avs check
FAILED	1113	cannot exceed sales cap
FAILED	2000	generic host error
FAILED	2001	invalid login
FAILED	2002	insufficient privilege or invalid amount
FAILED	2003	login blocked
FAILED	2004	login deactivated
DECLINED	2005	transaction type not allowed
FAILED	2006	unsupported processor
DECLINED	2007	invalid request message
FAILED	2008	invalid version
DECLINED	2010	payment type not supported
FAILED	2011	error starting transaction
FAILED	2012	error ending transaction
DECLINED	2013	error checking duplicate
EMPTY	2014	no records to settle
EMPTY	2015	no records to process
FAILED	99999	host error transaction not processed
FAILED	99999	undefined error