HTML_Template_ITX: callback functions

hi folks, i'm using itx for a long time and a few days ago i discovered the feature of callback-functions. the feature works fine inside of a row, but if i use it again after parsing the last row it outputs a empty row. it doesn't matter if i'm using the same callback-function as inside the row or another one. is this a bug or am i using the feature in a wrong way? the documentation isn't the best ... here are the links to my source-code: php-code: http://nopaste.php-q.net/14098 callback-functions: http://nopaste.php-q.net/14099 template: http://nopaste.php-q.net/14100 thanks a lot and sorry for my bad english ;) jens Nistler