Error:identifer "blockIdx" is undefined

My setup for CUDA

Visual Studio 2010 and 2008 SP1 (required by CUDA). Parallel NSight 1.51 CUDA 4.0 RC or 3.2 and Thrust

Basically, i followed the guide on: http://www.ademiller.com/blogs/tech/2011/03/using-cuda-and-thrust-with-visual-studio-2010/

I then proceeded to compile successfully without error messages.

So i tried with more CUDA code examples from the web. These errors surfaced on Visual Studios. I can still compile successfully without error messages but these errors are only visually highlighted

• "Error:identifer "blockIdx" is undfined."
• "Error:identifer "blockDim" is undfined."
• "Error:identifer "threadIdx" is undfined."

Here's the screenshot.

https://i.sstatic.net/v1LFx.png

Should i be concerned? Is it a Visual Studios bug or is my setup configuration wrong? Any help is appreciated. Thanks guys!

P.S I'm very new to both Visual Studios and CUDA.

// incrementArray.cu
#include "Hello.h"
#include <stdio.h>
#include <assert.h>
#include <cuda.h>
void incrementArrayOnHost(float *a, int N)
{
  int i;
  for (i=0; i < N; i++) a[i] = a[i]+1.f;
}
__global__ void incrementArrayOnDevice(float *a, int N)
{
  int idx = blockIdx.x*blockDim.x + threadIdx.x;
  if (idx<N) a[idx] = a[idx]+1.f;
}
int main(void)
{
  float *a_h, *b_h;           // pointers to host memory
  float *a_d;                 // pointer to device memory
  int i, N = 10;
  size_t size = N*sizeof(float);
  // allocate arrays on host
  a_h = (float *)malloc(size);
  b_h = (float *)malloc(size);
  // allocate array on device 
  cudaMalloc((void **) &a_d, size);
  // initialization of host data
  for (i=0; i<N; i++) a_h[i] = (float)i;
  // copy data from host