How to get positive response with PHP API for Purchase ?

Hi, 

I am using PHP API for purchase. I have downloaded the test code from github. I tried using the same values and tested. It is returning all null values. My concern is to how I would verify that all values are posted correctly and server executed them and return valid response. am I doing it correct or is there any other sample code with test credit card credentials to get positive response. Currently I am getting response with null values. Here is the response

CardType = null

TransAmount = null

TxnNumber = null

ReceiptId = Global Error Receipt

TransType = null

ReferenceNum = null

ResponseCode = null

ISO =

Message = Global Error Receipt

IsVisaDebit =

AuthCode = null

Complete = false

TransDate = null

TransTime = null

Ticket =

TimedOut = null

Thanks!!