MS Detours detoured function not being called - c++

Question

I'm working with MS detours 4.0, compiled in VS2005 on Windows 10 (Updating an older application).
I'm trying to detour the WriteProfileStringA function normally found in the kernel32.dll with a DLL injection.
The DLL injects just fine, I can debug the target process and can step through the detouring functions.
DetourTransactionBegin, DetourUpdateThread, DetourAttach and DetourTransactionCommit all pass with flying colours returning 0 each time.
typedef BOOL (__stdcall * WriteProfileStringAType)(CHAR *,LPCSTR,LPCSTR);
static WriteProfileStringAType OriginalWriteProfileStringA = NULL;
BOOL WINAPI DetouredWriteProfileStringA(CHAR * lpAppName,
LPCSTR lpKeyName,
LPCSTR lpString)
{
FILE* file = fopen("c:\\temp\\testdetour.txt","w");
fprintf(file,"DetouredWriteProfileStringA");
fclose(file);
return OriginalWriteProfileStringA(lpAppName,lpKeyName, lpString);
}
...
BOOL WINAPI DllMain(HINSTANCE hinst, DWORD dwReason, LPVOID reserved)
{
if (DetourIsHelperProcess()) {
return TRUE;
}
if (dwReason == DLL_PROCESS_ATTACH) {
...
DetourTransactionBegin();
long update = DetourUpdateThread(GetCurrentThread());
OriginalWriteProfileStringA = (WriteProfileStringAType)GetProcAddress(GetModuleHandle("kernel32"),
"WriteProfileStringA");
long attach = DetourAttach(&(PVOID&)OriginalWriteProfileStringA, DetouredWriteProfileStringA);
long commit = DetourTransactionCommit();
...
}
else if (dwReason == DLL_PROCESS_DETACH) {
DetourTransactionBegin();
DetourUpdateThread(GetCurrentThread());
DetourDetach(&(PVOID&)OriginalWriteProfileStringA, DetouredWriteProfileStringA);
DetourTransactionCommit();
}
return TRUE;
}
BUT when the target application calls the WriteProfileStringA function, the registry is updated but the detour function is never called, break points are ignored and the testdetour.txt isn't created in the c:\temp directory(which does exist)...
Anybody have any ideas?