Make certain you have all your DEFINES set up properly to tell PBP just
what pins you have connected to what.
Also, use some command and data delays.

Below is a header file I use. It works with every display I hook up.
You will have to change your pin definitions, of course.

DEFINE LCD_DREG PORTH
DEFINE LCD_DBIT 0
DEFINE LCD_RSREG PORTH
DEFINE LCD_RSBIT 5
DEFINE LCD_EREG PORTJ
DEFINE LCD_EBIT 2
DEFINE LCD_RWREG PORTH
DEFINE LCD_RWBIT 4
DEFINE LCD_BITS 4
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 3000
DEFINE LCD_DATAUS 300