Thrust::d Evice_vector can't assign a value?

In the C + + GPU Library thrust, there are two kinds of vectors

Thrust::d evice_vector<int> D; The GPU uses the in-memory vector thrust::host_vector<int> H;  In-memory vectors used by the CPU

Where host_vector can be initialized with constructors, such as:

Thrust::host_vector<int> H (10,1); Length is 10, each element is 1

But Device_vector does not compile all the way through ... Not understand ...

The example given on the official web site is possible:

Https://code.google.com/p/thrust/wiki/QuickStartGuide

The programmes currently in use are:

Construct the Host_vector and copy it to Device_vector

Thrust::d Evice_vector can't assign a value?