Synthesis ToolKit C++: FileRead::open: could not open or find file (rawwaves/sinewave.raw)

Visual Studio gives error: FileRead::open: could not open or find file (rawwaves/sinewave.raw) while using STK with C++ when debugging, but when running straight from executable, it works fine. Pre-Build commands:

mkdir $(TargetDir)rawwaves
copy $(SolutionDir)tools\stk-4.6.2\rawwaves $(TargetDir)rawwaves

The code (from tutorial):

#include "FileLoop.h"
#include "FileWvOut.h"
using namespace stk;

int main()
{
    Stk::setSampleRate(44100.0);
    FileLoop input;
    FileWvOut output;
    input.openFile("rawwaves/sinewave.raw", true);
    output.openFile("hellosine.wav", 1, FileWrite::FILE_WAV, Stk::STK_SINT16);
    input.setFrequency(440.0);
    for (int i = 0; i < 40000; i++)
        output.tick(input.tick());
    return 0;
}

Running from the .exe file in the output directory worked, but running directly from Visual Studio resulted in this: