load tree with checkbox

hi, i have use example http://webix.com/snippet/66c11a75 to loading my tree, but i have error : Maximum call stack size exceeded at this line:
hash2tree:function(hash, level){

Thanks

Please be sure that you have correct id->parent_id values. The error as above one can occur, if you have a loop in the data. Some item is marked as a parent of itself.