I am facing the same issue. Please take a look at the following code snippets.
SearchForm.php displays correctly if I comment the statement "//require_once 'includes/MessageTransactionReportGenerator.php';". However, if I uncomment it, I get a blank page. No error, no warning. I have included a snippet from MessageTransactionReportGenerator.php below. Note that MessageTransactionReportGenerator also has "require_once 'includes/MessageType.php';" statement.
I havent figured out any solution for that.
I will post back, if I do.
<?php
//file Name : SearchForm.php
require_once 'includes/PossibleValuesFinder.php';
require_once 'includes/MessageType.php';
//require_once 'includes/MessageTransactionReportGenerator.php';
...
And MessageTransactionReportGenerator.php looks as follows:
<?php
//file name: MessageTransationReportGenerator/php
require_once "includes/QueryExecutor.php";
require_once "includes/MessageType.php";
...