I also think you need to look at your CONFIG statement. PBP3 requires an indent and a double underscore to start the CONFIG statement and I don't think you can start a second line as you have done. Though if all you're trying to do is blink a light I'd leave all that stuff off and try it without.

RA0 is also a comparator input. On the 12F683 you need to turn the comparators off with CMCON = 7 and I think you need to do that with the CMxCON1 register. RA0 is also an input for a few other things and you'd think you wouldn't need to turn them off but you just might. One of the inputs is the ICSPDAT and the diode may be stopping the program loading. Try removing it, programm it, reinstall the LED and see if it works.

Also, if you didn't notice, wdmagic put the TRIS first and then the GPIO which I'm thinking is the preferred order. But they should come after the ANSEL, CMCON(if needed) and the OSCCON and DEFINE OSC settings.

If you think you might have the LED connected to a different pin on PORTA turn the whole port on with PORTA = %11111111.