LCD circuit help

I was trying to create the circuit found at the following link … rktime.htm

I had all the components except the 10K variable resistor, I think this is supposed to control the brightness of the screen. I only had a 47K variable resistor so I used that thinking it wouldn’t matter because it was just the brightness but my circuit isn’t working yet so I want to know if this is the likely cause?

I am trying to use a PIC 16f627 instead of the 16f84 so the mistake could possibly be in my modified code rather that the circuit.

I might be a bit late for this reply, but the 47K variable resistor should work fine in place of the 10k.
With the screen powered on, you should be able to adjust the variable resistor and see the characters go from blank to completely dark, this means your contrast is working and the problem likely lies with your code.
When I first tested my initialise code for an LCD I would set the contrast so that the characters were slightly dark, that way you can almost guarentee that you will be able to see the characters when they work.

Hope you find the problem.