Hi all, im trying to install ubuntu 64bits on the machine below but i always get a blank screen on it i have tried to boot with nomodeset and xforcevesa but no joy does anyone got the same problem???

Thanks to all in advance.

Toshiba Satellite L755D - 128
Processador : AMD A4-3300M APU with graphics Radeon HD 1.90GHz
Graphics: AMD RADEON HD 6480 G
Ram: 6Gb
HDD: 350Gb