I can't drive porta.4 high on this 16f627A, what am I missing?

All other pins on port A work fine (A.5 is input only)
Comparators are disabled
The TRISA is set to all 0's for output

Code:
define OSC 04               '4MHz internal oscilator 
clear
cmcon = 7                   
OPTION_REG.7 = 1            
trisa = 0
trisb = 0

main:
porta=255
pause 1000
porta=0
pause 1000
goto main

end