by searching here and there this one is suppose to be PBP compatible without too much problem. At least the controller is suppose to be HD44780 compliant.

Did you tried a longer start-up delay, let's say 2 Seconds at the top of the program?
Do you have another LCD to test with your current set-up?
What about the supply line? Clean and 5V?
what about your current setup? Any schematic or picture of it?

Maybe a simple hardware problem. unsufficient filtering or else.