[Typo3] Again: Hook "contentPostProc-all" in TSFE doesnt affect cached pages

[Christoph Singer]

Some time ago I wrote about the problem that a function manipulating
page content in the hook "contentPostProc-all" affects the page only
when it is generated for the first time after clearing all caches, but
not when it is viewed a second time. (Message ID
<mailman.1.1117486916.1188.typo3-english at lists.netfielders.de>, 30 May 2005)

Now I have installed the extension providing this function to another
Typo3 installation (same version, 3.8.0), it shows the same behavior
(first time the page is displayed correctly, second time without
modifications by the hook), but there is now an additional error message
when viewing the page the second time that could give the reason of this
behaviour:

<strong>ERROR:</strong> No class named: tx_lexikon_tsfeproc

tx_lexikon_tsfeproc is the class that provides the hook function.
It seems that this class is included correctly when generating the page
the first time, but is NOT included when it is loaded a second time.

This class is included and registered as described in the article "How
to use existing hooks" on typo3.org:

in file ext_localconf.php of my extension:
$GLOBALS
['TYPO3_CONF_VARS']['SC_OPTIONS']['tslib/class.tslib_fe.php']['contentPostProc-all'][]
= 'tx_lexikon_tsfeproc->processContent';

in file ext_tables.php of my extension:
require_once(t3lib_extMgm::extPath('lexikon').'class.tx_lexikon_tsfeproc.php');


Is there something I am missing? Do I need to do something else to
include this class when the page is loaded not the first time?

Thanks for any tips,

Christoph