K2 JSON format site node at beginning confused vData

Dear WDMTech,

I have a JSON source of K2 v2.8, my.site/categories?format=json
where categories is a menu item pointing to K2 Categories. The URL lists K2 categories beginning with:
{
"site": {
"url": "my.site",
"name": "My Site Name"
},
"items": [
{
"id": "3",
"title": "etc etc etc.",
......
At my another site with current vData installed, I want to import K2 categories. I created a new profile with K2 categories and remote server path my.site/categories?format=json
At field selection step it let me choose only "url" and "name", which is the header information. It would not let me choose the items in the "items" array which contain the real categories.

How can I make K2 not showing the "site" node or how to make vData skip "site" and read the fields in "items" array instead? Thank you.