filtering grid

I have a tree grid, and i have enabled text filtering on it. However when i enter some value in the text box, it thorws me error:

this.filterTreeBy is not a Function

I m using grid version 2.0.and have included the file dhtmlxgrid_filter.js

Do i need to include some other file where this function is defined?

To use filtering in treeGrid you should also include file from the dhtmlxTreeGrid package