VideoPortInt10 Reading EDID data

Hi,
I want to read EDID data using VideoPortInt10 function.

unsigned char EdidBuffer[128];

biosArguments.Eax = 0x4f15;
biosArguments.Ebx = 0x1;
biosArguments.Ecx = 0x0;
biosArguments.Edx = 0x0;
biosArguments.Edi = EdidBuffer; //4'th param
VideoDebugPrint((0," EdidBuffer[0] %x\n",EdidBuffer[0]));

status =VideoPortInt10(HwDeviceExtension, &biosArguments);

if(status==NO_ERROR && (biosArguments.Eax == 0x004f) )
VideoDebugPrint((0," biosArguments.Ax %x\n",biosArguments.Eax));
else
VideoDebugPrint((0," biosArguments.Ax %x\n",biosArguments.Eax));

I am getting successful in Ax = 0x4f.
But I am not able to get any data in EdidBuffer..............


Please help me out in using this function.
How can I read the EDID data.

Regards