Error code 103 - (TESTMODE) This transaction cannot be accepted on Authorize.net

To use Authorize.Net with Wahmcart, you must turn the password required mode off inside your Authorize.Net account. Please review the help documentation inside your account to find out how to do that.

Here's where to find the documentation. Log into your Wahmcart account, Click on Help, on the popup window click on System Setup >> Authorize.net Setup.

Also, make sure you entered the correct credentials in the Merchant setup.