Bad DLL Calling Convention in Excel - c++

Question

I have tried the tricks posted here (at least the ones I have found), but I still can't seem to rid myself of the dreaded "Bad DLL Calling Convention" error. Here is my (very simple) c++ code:
VRTTCONVERSION_API long controlVTT(BYTE controlVal, BYTE valueVal)
{
LPSTR controlStr = new char[256];
PCHAR convstrout = new char[256];
if (controlVal == 1) {
controlStr = "Ping";
}else if (controlVal == 2) {
controlStr = "0 Init Tool Default";
}
if (bGetGeneralAccessFunctionPointer()) {
return (pGeneral)(controlStr, convstrout, 256);
}
else {
printf("failed to acquire function pointer.\n");
return -1;
}
}
This SHOULD accept bytes as inputs and return a long. I know the return works as I have another function that doesn't accept any inputs and returns the long and that one works fine.
Here is the VBA code (again, simple):
Public Declare PtrSafe Function controlVTT Lib "VRTTConversionDLL.dll" Alias "#4" (ByVal controlVal As Byte, ByVal valueVal As Byte) As Long
Sub testControl()
Dim retval As Long
Dim bFunc As Byte
Dim bVal As Byte
bVal = 0
bFunc = 1
retval = controlVTT(bFunc, bVal)
MsgBox retval
bFunc = 2
retval = controlVTT(bFunc, bVal)
MsgBox retval
End Sub
I know the #4 alias is correct (from using DLL Export Viewer). This function also works when I call it from another C++ function (see below):
int main()
{
long retVal;
retVal = controlVTT(1, 0);
printf("Return: %08X \n", retVal);
retVal = controlVTT(2, 0);
printf("Return: %08X \n", retVal);
return 0; return 0;
}
Obviously, I'm not a professional programmer and I'm probably missing something basic, but I am truly stuck.