Loading effect of microcontroller P89V51RD2

I have used P89V51RD2 to drive my power mosfet 804, as the output voltage of Microcontroller is only 5V it is not triggering the mosfet which should be above 7V. Hence i planned to attach a optocoupler. but when i connect the output pin P1^1 to the 1st pin of optocoupler through a 47 resistor. the microcontroller output drops to 0.75V. this happens when the 2nd pin and the 4th pin of optocoupler are connected through a 100 ohm resistor, as per circuit this pin has to be grounded, the microcontroller value drops when this grounding is done. Can anyone help me with this issue!!!