Where is my parent?

Dear All, Is there a way to re-write a method in parent class and still access the parent class by parent::method()? I have a class (classChild) extended from another class (classParent). In classChild I have re-implemented method foo() as a wrapper function of method foo() in classParent. Method foo() in classChild calls method foo() in classParent by parent::foo(). The scheme works out fine when I test it by writing a shell script that runs a CGI version of php. But when I run it through apache module, I got a fatal error saying 'No parent class available in this context'. I have made sure the parent class file is included, and the classChild 'EXTENDS' the classParent. Now, where is my parent? Thanks in advance for any comment and suggestion. Chien-pin P.S.: PHP CGI version is 4.0.2, apache module version is 4.0.4pl1