🚀 go-pugleaf

Hello! ...

I'm workin' with DES on C++ Builder 5. When I try to change MediaSubType of 
one Video Group appears this "fatal error" messange:

Project Projecto1.exe raised exception class EAccessViolation with messange 
'Access violation at adress BAADF00D. Read of address BAADF00D'. Process 
stoped. Use Step or Run to continue.

This is the Code:

AM_MEDIA_TYPE mtGroup;
mtGroup.majortype = MEDIATYPE_Video;
mtGroup.subtype = MEDIASUBTYPE_RGB555;

mtGroup.pbFormat = (BYTE*)CoTaskMemAlloc(sizeof(VIDEOINFOHEADER));


VIDEOINFOHEADER *pVideoHeader = (VIDEOINFOHEADER*)mtGroup.pbFormat;
ZeroMemory(pVideoHeader, sizeof(VIDEOINFOHEADER));
pVideoHeader->bmiHeader.biBitCount = 16;
pVideoHeader->bmiHeader.biWidth = 320;
pVideoHeader->bmiHeader.biHeight = 240;
pVideoHeader->bmiHeader.biPlanes = 1;
pVideoHeader->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pVideoHeader->bmiHeader.biSizeImage = DIBSIZE(pVideoHeader->bmiHeader);

mtGroup.formattype = FORMAT_VideoInfo;
mtGroup.cbFormat = sizeof(VIDEOINFOHEADER);

mtGroup.bFixedSizeSamples = TRUE;
mtGroup.lSampleSize = DIBSIZE(pVideoHeader->bmiHeader);

IAMTimelineGroup        *pGroup;

pGroup->SetMediaType(&mtGroup);

CoTaskMemFree(mtGroup.pbFormat);

And the error appears when I add this line: pGroup->SetMediaType(&mtGroup);

Could anyone explain me why this error appears?!!?

Thanks!!!
Juampi David