Dnn with inference engine

Hello, I have donwloaded opencv binaries from

for testing dnn with inference engine

But I call dnn::getAvailableBackends() function, and the answer I get (formatted) is this
Available: BackEnd: 1000000, Target: 0
Available: BackEnd: 3, Target: 1
Available: BackEnd: 3, Target: 2
Available: BackEnd: 3, Target: 0

where backend 3 is DNN_BACKEND_OPENCV.
Number 2, that corresponds to DNN_BACKEND_INFERENCE_ENGINE,
does not appear in list.

What can be wrong? Any idea?