请检查名为OffWFCommon的feature是否已经被activated.
如果没有, 那么就请运行如下的命令:
stsadm -o activatefeature -url http://sharepointsite -force -name OffWFCommon
参考资料
=================
Custom workflow does not start. Feature needed.
http://lawo.wordpress.com/2009/06/21/assigned-workflow-does-not-start/