ATtiny85 simulation in AtmelStudio 6.1 (build 2730, SP2)
The ATtiny85 has no pin PB6 and PB7 so you are trying to address hardware pins that simply aren't there. According to the datasheet (paragraph 10.4.2 - 10.4.4) these bits for DDRB, PINB and PORTB are always 0.