Error when using zend debugger + zend optimizer

[ho__oh]

I'm using php5.2.9 with both zend debugger and zend optimizer. The web application can run in normal mode but when i try debugging by zend debugger, the zend optimizer does not run and this error occurs 'Use of undefined constant Zend - assumed 'Zend'. Please help me!

[ho__oh]

No one help me? Please help me, now i have to debug by watching code line and that really painful !