Hi,
you are trying to access DDC EEPROM through VGA connector.EEPROM contains information about the video timings,supported format (EDID data )....etc
Address of EEPROM is 0xA0 , most of them are write protected. Only reead operation is available. It ıs usually 128 byte but some devices has extended version of EDID data so data length is 256. But to access second 128 byte you must use 0xA2
First using these address above, try to get ACK from device. You may search internet for special EEPROMs for DDC like 24LC21