PHP Mess detector - 当内部状态被冻结时，无法创建新节点

I am tring to run phpmd like this:

wget -c http://static.phpmd.org/php/latest/phpmd.phar
php phpmd.phar ./src text cleancode codesize

I get the following error message and I don't know what to do.

Cannot create new nodes, when internal state is frozen.