Hi Nicolas,
Thanks for your input on this. The whole VM payment plugin was a confusing and frustrating situation for me do to the lack of documentation and conflicts in VM's documentation which I will explain below, but I finally got it figured out.
I thought I would post my situation incase others in the future ever find themselves in this situation with the VirtualMerchant Payment Plugin.
It turns out as you mentioned Nicolas, when you choose the "Sandbox" mode on in the payment plugin that makes the plugin send data to demo.virtualmerchant.com, which is correct in that VM needs to set up a test account, and when you disable "Sandbox" in the payment plugin it uses just virtualmercant.com to send data to a production account.
BUT, where things got screwed up and conflicted is that I actually contacted VM personally, and even though there own documentation states to contact them to set up a test account. When I called them they kept insisting that a test account is not necessary? I had to call three times until I did got a rep who was intelligent enough to convert the production account I was working with on their end to a test account. So the rep converted the production account that was given to me to use so it was in "TEST MODE" as they put it.
Sooooo you would think that at that point the issue has been settled and I could go on my merry way with testing transactions. So as one would think and if someone is following all the documentation. You would think that now that VM set up the account to be in "TEST MODE" that you would set the VM payment plugin to have "Sandbox" enabled. But that is not the case. ss I mentioned above when sandbox is enabled it changes the url that data is sent to. But it turns out after a couple hours of frustration , I discovered that after VM changed the account to run in TEST MODE, that you must have "Sandbox" DISABLED in the payment plugin so that it still sends data to the production url.
long story short, the "Sandbox" option in the payment plugin proved useless and actually made things more confusing in my situation. And in the end what you must do if you want to test transactions using the VM payment plugin is to leave "Sandbox" DISABLED and contact VirtualMerchant. Ask them to set up the account in "TEST MODE" and perform all you test transactions. Then you must call VM back when you are done testing and have them convert the account back into a "PRODUCTION" account.