Turning on Multisampling

Despite the shader issues, I would like to turn on multisampling. I have modified the gfxD3DDevice.cpp code (GFXD3DDevice::setupPresentParams) thusly:

// @tsphillips Turned on multisampling.
   d3dpp.MultiSampleType  = D3DMULTISAMPLE_NONE; // default
   d3dpp.MultiSampleQuality = 0; // default
   D3DMULTISAMPLE_TYPE mst = D3DMULTISAMPLE_2_SAMPLES;
   DWORD quality = 0;
   if (SUCCEEDED(mD3D->CheckDeviceMultiSampleType(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, D3DFMT_X8R8G8B8, true, mst, &quality)))
   {
	   if (SUCCEEDED(mD3D->CheckDeviceMultiSampleType(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, D3DFMT_D24S8, true, mst, &quality)))
	   {
		   d3dpp.MultiSampleType  = D3DMULTISAMPLE_2_SAMPLES;
                   d3dpp.MultiSampleQuality = 0; // 0
                   Platform::AlertOK("Multisampling Enabled", "Multisampling has been enabled.");
	   } else {
                   Platform::AlertOK("Multisampling Failed", "Multisampling not supported for depth buffer format.");
	   } // if-else
   } else {
           Platform::AlertOK("Multisampling Failed", "Multisampling not supported for back buffer format.");
   } // if-else

This code runs successfully, but the success dialog is then followed by a failure message (in GFXD3DDevice::init):

// Gracefully die if they can't give us a device.
   if(!mD3DDevice)
   {
	   Platform::AlertOK("DirectX Error!", "Failed to initialize Direct3D! Make sure you have DirectX 9 installed, and "
                                           "are running a graphics card that supports Pixel Shader 1.1.");
	   Platform::forceShutdown(1);
   }

Does anyone know why the device would fail to initialize after enabling multisamping? If something is wrong, shouldn't some other error be reported before this point? (BTW, I'm running this on a GeForce 5200 FX.)

Tom