PHPUnit Fatal Error with Selenium/Ubuntu

I have gone through various tutorials/posts to install PHPUnit with Selenium on my Ubuntu system. I believe I have everything setup as required:

/usr/share/php$ phpunit --version
 PHPUnit 3.6.10 by Sebastian Bergmann.
 

So using the IDE I create my test, and save it for running, which appears to be setup as required. So I run the test using:

phpunit /home/retrobadger/working_files/tutorials/phpunit/selenium1.php
 

But everytime I run it, I get the error below:

PHP Fatal error:  Class 'PHPUnit_Extensions_SeleniumTestSuite' not found in /usr/share/php/PHPUnit/Extensions/SeleniumTestCase.php on line 394
 PHP Stack trace:
 PHP   1. {main}() /usr/bin/phpunit:0
 PHP   2. PHPUnit_TextUI_Command::main() /usr/bin/phpunit:46
 PHP   3. PHPUnit_TextUI_Command->run() /usr/share/php/PHPUnit/TextUI/Command.php:130
 PHP   4. PHPUnit_Runner_BaseTestRunner->getTest() /usr/share/php/PHPUnit/TextUI/Command.php:150
 PHP   5. ReflectionMethod->invoke() /usr/share/php/PHPUnit/Runner/BaseTestRunner.php:124
 PHP   6. PHPUnit_Extensions_SeleniumTestCase::suite() /usr/share/php/PHPUnit/Extensions/SeleniumTestCase.php:0
 

The file in extensions exists, and I have set very open priviledges to it. The only things I can think of are that either my SeleniumTestCase.php is faulty, or that I need to require another file no other tutorials have suggested.

Any recommendations would be greatly appreciated. I have little experience with PHPUnit so expect my mistake is a basic one.

Thanks for any advice you can give,
Dan

---