CreateChannelDesc fails on cuda-2.0 OK on cuda-1.1 CreateChannelDesc returns NULL array

When I compile and run the following code on CUDA-1.1 it succeeds
When compiled and run on CUDA-2.0 it fails because the array returned is NULL

It only seems to be a runtime problem.
When I compile with CUDA-2.0 but run with LD_LIBRARY_PATH pointing to cuda-1.1 it succeeds too.

#include <stdio.h>
#include <cutil.h>
int
main(int argc, const char ** argv )
{
int width=1024,height=768;
cudaArray *_array=NULL;
cudaChannelFormatDesc channelDesc = cudaCreateChannelDesc();
CUDA_SAFE_CALL( cudaMallocArray( &_array, &channelDesc, width, height));
if(_array==NULL)
printf(“ERROR _array = 0x%x\n”,_array);
else
printf(“SUCCESS _array = 0x%x\n”,_array);
return 0;
}

Because of this problem the
“Optical Flow Algorithm using CUDA and OpenCV” example found at
http://www.nvidia.com/object/cuda_home.html

only works on CUDA-1.1 for me.
See code snippet below:

Any ideas, what the problem might be?

Greetings,
Martin

Optical Flow Algorithm using CUDA and OpenCV

template
void
Array::init(CvSize size)
{
dealloc();
_size = size;
_refCount = new int;
*_refCount = 1;
// Allocate array
cudaChannelFormatDesc channelDesc = cudaCreateChannelDesc();
CUDA_SAFE_CALL( cudaMallocArray( &_array, &channelDesc, size.width, size.height));
assert(_array != NULL);
}

Array arr(size);//this results in assert going off