i have fixed the circuit from that page and work fine.

http://www.radiolocman.com/shem/sche....html?di=44132

he is using the following

LcdReg = %00100001 'LCD Extended Commands.
call PrintCtrlLcd
LcdReg = %10101001 'Set LCD Vop (Contrast).
call PrintCtrlLcd
LcdReg = %00000110 'Set Temp coefficent.
call PrintCtrlLcd
LcdReg = %00010011 'LCD bias mode 1:48.
call PrintCtrlLcd
LcdReg = %00100000 'LCD Standard Commands, Horizontal addressing mode.
call PrintCtrlLcd

that means that the HEX of the Vop is $A9.

He is also says:

If by any chance the contrast isn't to your liking, it can be changed during the programming of Pic12F629, in the program location D2h. the current value A9h is the one I use with my LCD and don't know it will be for other LCDs. The value can be set to anything between 80 h and FFh, 80 h being minimum contrast and FFh maximum.