need help data connection

i  purchase a galaxy s 3 weeks ago
when i try to put a simcard of globe  that has a plan on it  which is a 128k simcard  the internet connection is working  and the im seeing 3g or  gsm or edge my phone on top  near the signal bars
but when i try to insert  a prepaid sim into it which (also globe) is a 68k sim card which has a 3g capabilities which i also try it on my nokia e72 its working but on the  galaxy s its not .. need help

they given me the apn settings for globe.. but still its not working