Regardless of the activation in This is a Custom Makefile in the property options the Build->Export Makefile is disable, Am I wrong or is a trouble with the 8.02v of CodeBlocks??? thank!!! :P
It was disabled a long time ago. You may want to try the Makefile Generator plugin:
Forum thread (http://forums.next.codeblocks.org/index.php/topic,6241.0.html)
Project's page (http://developer.berlios.de/projects/cbmakegen/)