مشکل با Zend

من نسخه ی 4.5.4 را به صورت لوکال با استفاده از دو نرم افزار EasyPHP 1.7 و WampServer (یعنی دو بار ) بر روی کامپیوترم نصب کردم ولی در هر دو حالت error زیر رانمایش می دهد ، علت چیست ؟
Zend Optimizer not installed
This file was encoded by the Zend Encoder / Zend SafeGuard Suite

In order to run it, please install the freely available Zend Optimizer, version 2.1.0 or later.

What is the Zend Optimizer?
The Zend Optimizer is one of the most popular PHP plugins for performance-improvement, and has been freely available since the early days of PHP 4. It improves performance by taking PHP's intermediate code through multiple Optimization Passes, which replace inefficient code patterns with efficient code blocks. The replacement code blocks perform exactly the same operations as the original code, only faster.