Geb: Switching URL with go() method

I am getting the URL(href attribute of link tag) of a link want to switch to it by:

def hotelDetailsPage = result[0].getAttribute("href")
println hotelDetailsPage // Showing the url perfectly
go(hotelDetailsPage)

But getting error:

Condition not satisfied:

go(hotelDetailsPage)
|  |
|  http://ift.tt/2cH3hC7
null

    at xxx.IntlHotel.Test.IntlHotelHomePageTest.Select origin(IntlHotelHomePageTest.groovy:138)

How to solve it and switch to the url?