I have purchased a Blackberry Bold 9000 from eBay. It is unlocked and I currently have my Optus Pre-Paid sim in it. I have the Turbo Cap offer which includes 100mb of data. Each time I try to use the browser it tells me that 'There is insufficient network coverage to process your request' I can connect to my computers wi-fi perfectly, why does my BB internet not work?

Help please.