W3 TC page cache enabled but not working

Hello,

after wp super cache stopped working for me, I tried alternatives and the last (best) one was W3 Total Cache. But the most important feature = page cache dows not work for me although I think I made everything right in settings. But Database Caching is working, at least there are directories/files in the db cache directory.. in the page cache directoriy there are no files but htaccess.

Debug info from home page – which should be cached:

<!– W3 Total Cache: Page cache debug info:
Engine: disk: enhanced
Cache key: _index.html
Caching: disabled
Reject reason: DONOTCACHEPAGE constant is defined
Status: not cached
Creation Time: 0.843s
Header info:
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
X-Pingback: http://URL.de/xmlrpc.php
Content-Type: text/html; charset=UTF-8
X-Powered-By: W3 Total Cache/0.9.2.5
–>

Debug info from article page, which should also be cached:

<!– W3 Total Cache: Page cache debug info:
Engine: disk: enhanced
Cache key: 2013/01/game-tipp-interference-fur-windows-phone-und-windows-8/_index.html
Caching: disabled
Reject reason: DONOTCACHEPAGE constant is defined
Status: not cached
Creation Time: 0.461s
Header info:
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
X-Pingback: http://URL.de/xmlrpc.php
Content-Type: text/html; charset=UTF-8
X-Powered-By: W3 Total Cache/0.9.2.5
Link: <http://wparea.de/?p=26729&gt;; rel=shortlink
–>

http://wordpress.org/extend/plugins/w3-total-cache/