C++ :: Converting Strings In Application

I am having trouble converting strings in my application.

This is the code that is eventually getting called, the first parameter takes a LPCWSTR

Code:
hr = m_pGraph->RenderFile(m_filePath, NULL); // takes LPCWSTR This is where the trouble begins.

The compiler shows that sResult is proper but after I try to convert a std::string to a wchar it prints garbage

Code: const wchar_t* m_filePath = (wchar_t *) oDb->GetNext().c_str();

Code:
std::string CSqlLiteDatabase::GetNext() {
sqlite3_stmt *oStmt = nullptr;
std::string sql = "SELECT path || filename FROM table WHERE id = 1";
char message[255];

[Code] ....