calling CUDA API using C

[sprb]

i want to call a cuda API NVGetHWEncodeCaps and write my code in visual studio 2008 and have these error,can u help me? I add the library and header file.
code:

int main()
{
HRESULT hr = NVGetHWEncodeCaps();
if (FAILED(hr))
{
printf("failed"+hr);
}
else
printf("ok"+hr);

getch();
return 0;
}

errors:
unresolved external symbol NVGetHWEncodeCaps referenced in function main
fatal error LNK1120: 1 unresolved externals