My 8800 not connecting to Network

I received a bb8800 that is not connecting to the network. any network.

the service book tell me it was used on the Digicel jamaica network.

The network lock was cleared but I cannot connect to any network in jamaica, whether LIME, or CLARO or even DIGICEL.

everything else on the phone seems to work except the network connection.

when i use manual search, it timed out before a connection can be found. I'm at my wits end. A little help please.

What service did you activate? Is the SIM card properly inserted?

I have a similar problem. I live in South Africa and I bought an unlocked 8820 from America (Original carrier:AT&T), It worked fine on my local carrier (Cell-C) until I upgraded it to BB OS v4.5 - It now does not pick-up any of the South African Mobile Networks including Cell-C. When I downgraded the OS back to BB OS v4.2 it worked fine again... Please help.