HELP PLEASE NEO2!!!

[Brado]

i have brought a neo2 ps2 modchip, i have a euro ps2 i live in australia, i have installed the chip and it seems to play CDR ps1 games ok, haven't try CDR ps2 games yet, but it won't play the original ps2 games?? it loads the ps2 logo screen then hangs, if i take the chip out it is the opposite, lets me play ps2 and no backups? please anyone help?????