Hi Tei,

Your code should work as-is, but if you can provide a little more information, it helps list members to help you isolate the problem.

What oscillator speed are you using?
Are you using the internal RC osc or an external crystal or resonator?
Do you have a pull-up resistor from Vcc to /MCLR or do you have /MCLR disabled?
What type of 3V power supply are you using?
Have you managed to get an LED to blink at all to test your circuit?