FTS - Date Range Query

Hi All, (sorry for my english)
I have a project with couchbase node.js sdk.
I use the full-text search index.
The documents have a field type datetime (name “updateAt”).
I want use the function DateRangeQuery to query the filed “updateAt”, but I do not know how to implement it.
In the official docs there is not a example.
Can you help me please?

i have resolve the following question:
i have set by mistake in the index the field “updateAt” at a text, now i have set at datetime and now i have the response.

I have another question: i tried to use the datetime in the full-text search in developer web console too, (with the querystring query obviously), but i have the problems here too.
I explain:
i have this documents with this fields "updateAt":
> "updateAt":"2018-01-19"
> "updateAt": "2018-01-19T00:00:00.000Z" 

I Search, for example, with this query:

> updateAt: >"2018-01-01"

but I do not receive anything.
What am i doing wrong?